I have a 1997 chevy 3500 van and I needed new tumblers and the ignition module so I need to know how to get the sterring wheel off to change the module then I can put it back on again

If it has an airbag.. I would let a dealership do it. Its not fun to have one of those go off in your face (or even near it)

If no airbag, look on the backside of the steering wheel for bolts.. that should remove the cover, then there are bolts in there.

The Supplemental Inflatable Restraint system can be disabled at the bottom of the steering column by unplugging the yellow connector.
Then the airbag can be removed without fear of deployment.
Once the air bag is removed, you'll need some special tools: one to remove the steering wheel and another to remove the lock plate. If you're still interested, let me know and I'll go into the steps, but only if you're really certain you can complete the job.

I know its been a while.. but don't you need to disconnect the battery if you are going to remove it??

Wait.. sorry. My mistake. It's the airbag MODULE that can cause the problem. If you plug that in while the battery is connected then it can deploy the air bags. CaptainRich is correct :)