What it does ?
When a pressure plate is triggered and a sign if found under, the command writed on the sign makes the player perform the given command.
Plate a pressure plate (wood/stone/iron/gold) And one block under the pressure plate, place a sign with:
Lines2-4 insert the command here
If you want the command: /warp goto myNewSuperGiantPigFarm
2> warp goto myNew