I think my first online income was from selling used books. I would buy books at thrift stores, garage sales, auctions, etc. and sell them over the Internet. It was pretty exciting to buy a book for a dollar and sell it for $200! Rare, true, but exciting when it happened.
I had so much to learn! I had NO idea how to make a web site. None. I bought a domain name, or thought I bought one, actually the guy I used to register it registered it in his own name. I didn't know the difference. And once the domain name was registered, and I started paying for web hosting, I didn't have a clue about how to make the site or get anything to happen online. I didn't know about FTP or HTML or anything!
Even when I started a more successful project, selling a book I wrote myself, I began with using the old AOL Homepage function, and having people send me a paper check in the mail to a PO Box to order a hard copy of the book.
I did learn, though.