Mystic Crunk

Hello, I am fairly new to windows 2003 and have a server running it. I currently have a forum installed where people can upload small video clips. Well anyway to my point, when I try posting something I get an error "Fatal error: Maximum execution time of 30 seconds exceeded in etc....." I was wondering where I am able to change this 30 second setting. I currently have plesk installed. Thanks, and any help is appreciated. Dan Crunk