Bukkit

How do I create a ready arena?

Easy, create a new arena and then you need at least 1 spawn point for each team ( Blue, Red and Spectators(!) ). The commands for that are in the command list. Or simple type "/pb arena" in game to get an overview over all possible arena commands. Don't forget, that you also need a lobby to start playing paintball! And there has to be PvP enabled in the world/arena/server, as the hits wouldn't be detected otherwise.
Hint:
Creating an arena with these commands has nothing to do with the building of the arena! You can build your arena exactly the way you want it. But take care when possible structural, that other minecraft players (not participating in the match) can't enter the arena or the terrain and could disrupt the match.

When I join a team it says, that no arena is ready.

You likely forgot one of the 3 necessary spawn points (maybe the spectator spawn point?). With "/pb arena [name] info" you can get information about, why the arena is marked as "not-ready".

Why do I need a lobby?

The lobby is some kind of interface between the normal survival gameplay on the server and paintball. By entering the lobby, various things are blocked (item collecting, ..) and be assured that survival and paintball are not mixed. Therefore, the lobby should be structurally impenetrable (like the arenas too), so nobody can enter or leave without using the leave command.

The snowballs do not hit!

If the balls seem to do not hit it's very likely that the world/server the arena is in does not have pvp enabled (set to true). It needs to have pvp=true in the world/arena to be able to detect the ball hits. If the balls do not hit, but pvp is enabled and if you try to leave the lobby it says "you are not in the lobby", then you probably use CommandSigns. Don't use it. It currently makes strange problems with minigame plugins.

I try to change the language, but it doesn't work!

Do not replace or overwrite the default language file, it will be replaced on each reload. Create a new file and edit the config.yml. There are several reasons that could be causing the plugin to not use your custom language file. In every case it will (try to) tell you why it uses the default language file instead in the server log. So check the log! Another hint: Depending on your system, the language file can sometimes not be loaded because of special characters in it. This can even create "fake errors" saying "somthing is missing" etc., but the real problem are the special characters. So if problems occur with the loading of your language file, check it for special characters and replace them first.

How can I modify the shop?

You can change that in the config.yml (check out the configuration documentation) of the plugin. Simply follow the pattern there. If you make mistakes, the corresponding slot is shown as <empyt> in-game.

My players can't leave the lobby!

You have very probably AutoLobby (or WorldMode) enabled inside the config. This setting is meant for paintball-only servers, that's why players can't leave the lobby. If you want them to be able to leave the lobby -> disable this setting.

The time until a new round begins is taking too long!

You can change the duration of the countdown between matches in the config.yml too!

What are the permissions? What is the permission for playing paintball?

Take a look here.

How can I create signs with stats (points and such) on it?

You (the admin/ a player with admin permission) can create them by putting for example "[PB POINTS]" at the first line of a sign. If it was sucessfully, players can now simple click the sign, and it will generate itself. The sign will be update each time a player clicks on it.
Notice: The following values are too long to put on a sign so they were replaced by something shorter:
teamattacks->"ta" ; hitquote->"hq" ; airstrike->"as" ; money_spent->"spent"

How do I use this "Individual Signs" plugin?

You can get it here. It's only optional and it allows you to create signs displaying most stats values for each player independently.
You use it very similar to the normal paintball stats signs, but with "_" instead of a space on the signs first line.
To use it simple put something like this on your sign: "[PB_STAT]" where STAT is the name of the stats value you want to display.
To create a sign with this on it, you need the the paintball.admin permission.
Example: "[PB_POINTS]"
If it worked the sign will immediately change after creation. If it does not, its very likely that you made something wrong:
Maybe you put some not-existing/ not-supported stats value there instead?

Why is the paintball money separated from the servers economy money?

Because this plugin was created with the aim to easily being able to run it additionally on any normal survival server. On a normal survival server players usually have a wide range of possibilities how to earn and how to spend money. Adding paintball as a new way of earning and spending money makes it a lot more difficulty to properly balance the economy on the server:
If it is to easy to get money or if the stuff in the paintball shop is too cheap players can basically buy whatever they want from the paintball shop whenever they want, making it no fun to play.
And if it is to difficulty to gain money or if the stuff in the paintball shop is too expensive players will always have to decide if they are really willing to spend their hardly earned money on the temporary and transient stuff from the paintball shop or instead investing it on the survival part of the server.
With a separate and a lot simpler economy for paintball it is a lot easier to guarantee that players really spend their earned money on stuff from the paintball shop and on the other hand it's also easier to balance the paintball shop so that players can only spend that much money on those advantageous paintball gadgets as they have earned through playing paintball.

Why is there no setting for using the server economy for paintball? Why is there no easy way for exchanging server economy money to paintball money?

Many servers sell their server economy money for real money to players nowadays. With a setting to use this server economy money directly in paintball or an easy way for letting players exchange the bought server economy money for paintball money would make it a lot easier for servers to abuse those features for breaking the usage conditions of paintball (which state 'no commercial usage' and 'no benefits for paying players').
There is only a very limited amount of valid usecases for this: For example it could be useful for servers which are oriented around minigames only and which don't sell their server economy to their players.
However due to those servers which abused this in the past it was decided to not include this for now.
As a compromise you can however configure paintball to additionally reward players in your servers economy.