As in how to use the software or as in how to actually complete an 1120?

Then you might want to learn like most of us did.  Get a copy of the instructions and work your way through.

"I have the income statement and the balance sheet."

And what about the rest of the info you need? Assets new in service, assets removed from service, prior depreciation, etc? I doubt your instructor would appreciate you asking on the internet How To do something they should be teaching you and you should be learning. If asking the internet was all that is required, there would be no need for classes or certification.