Forum Moderators: buckworks
oscommerce is set-up for those tasks, and if you can't figure it out, most developers and other users won't help you. If you can't figure that out by yourself, you haven't seen the end of your troubles.
As to what you do from here... you can go back to the docs to try and figure out how to do it. Or, you can hire a developer to set up oscommerce for you. Failing that, I recommend you go with a hosted shopping cart such as Yahoo's which won't require technical knowledge on your part.
I hope that helps; good luck!