What do you need to download to make a .jar file

In order to make a jar file you have to run a command in the "jar utility." Which it sounded like was just the command prompt. Yeah it's not. if you try the command prompt will just say "jar" is not recognized as an internal or external command. I thought it was gonna say that but it was worth a try. So is there some sort of command line program that i have to download or what?

thanks, lateralus

[412 byte] By [Lateralus01a] at [2007-11-26 22:36:59]