Need to replace the seals on an old Crossman co2 revolver. I dont even know where to begin...

Call Crosman. They have a customer service department just for times like this. Just Google them.

I will try that, thank you.

How old, is old? I have a c02 revolver and it wouldn't hold pressure and leak the cylinder dry pretty quick.
Took it apart, went to Ace Hardware and for 52 cents I bought new o-rings. Needed two and taped the other two under the grip.