How do you change head gasket on a 1994 vauxhall corsa?

unless you know what your doing be careful.

get a haynes manual for the car should tell you in there.

Or...

Get a friend to help you with this, stand by the open drivers window, get a mate to push the back of the car, lift the handbrake off and push it to your local scrap dealer and weigh it in, a new head will proberly cost enough to not bother fixing it, so use the weigh in money and the money you would spend and get a new car