Craigslist business, how do you file?

Well, I just been buying and selling stuff off craigslist and eBay I buy or get for free for like a year. I have no receipts, i never did taxes before, or had to, my uncle use to do it. Thought it would be ez to do, but they talking about receipts and 1090 forms?? What is easiest way to do for free and what forms? Thanks for help