Bukkit

I'm on the right Bukkit Version and Stuff but I'm getting a mistake so i can't use it in anyway. What can I do?

18:08:32 [SCHWERWIEGEND] Could not load 'plugins/Drinks.jar' in folder 'plugins' org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: me/mm1990d/Beer/Beer : Unsupported major.minor version 51.0 at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:154) at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:305) at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:230) at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:222) at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:198) at net.minecraft.server.ServerConfigurationManagerAbstract.<init>(ServerConfigurationManagerAbstract.java:50) at net.minecraft.server.ServerConfigurationManager.<init>(SourceFile:11) at net.minecraft.server.DedicatedServer.init(DedicatedServer.java:105) at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:378) at net.minecraft.server.ThreadServerApplication.run(SourceFile:539) Caused by: java.lang.UnsupportedClassVersionError: me/mm1990d/Beer/Beer : Unsupported major.minor version 51.0 at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:634) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) at java.net.URLClassLoader.defineClass(URLClassLoader.java:277) at java.net.URLClassLoader.access$000(URLClassLoader.java:73) at java.net.URLClassLoader$1.run(URLClassLoader.java:212) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205) at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:44) at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:29) at java.lang.ClassLoader.loadClass(ClassLoader.java:321) at java.lang.ClassLoader.loadClass(ClassLoader.java:266) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:264) at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:143) ... 9 more

I really want that plugin :'(