I need big help!!!

Hey World,
I need to get the rear gear hub thing off my mountain bike wheel. I know there has to be a tool for it but if I can is ther a way to make a tool or get it off without one? My rig is down and I hate walking every where...give me some help!!! Thanx yall.....

thanx...I hope this will play I got crappy dial up...lol. Wil do much reading too.....

Went to link,lots to learn,thanx for the help.Now I got to go get the tools I need..

hey,got it somewhat fixed...used a plug socket turned backwards and a pipe wrench to turn it off. Held the gear teeth with a shop rag and a big pipe wrench. its ghetto but it worked.my axle is still bent and my cassette has about 5 mm play in it but it's all i got so i am going to deal with it....will try to replace later on. it sat in the rain for 2 years and all the bearing were shot and it acted like i was peddaling with the brakes on all the time....thanx fair...big help.