I did the tutorial on how to make a user registration system, however I need additional help.

I understand how to setup a user registration system but I need help with AFTER they register. I'll explain my scenario:

I have a website that sells items that require users to upload pictures and copy(paragraphs/text) related to the item. After they register how do I make it so users can select my item and upload their content. Then after they upload their content it stores all THEIR content on the database?

I need to make it so I can pull down each user's content i.e. pictures and text from the database.

Please help out a.s.a.p. thank you.