How to finde affliate products for my yahoo store?

[Moik]

Hi!
I am into internet marketing for a year, I am overwhelmed from info what I red, I made few blogs with adsense, few blogs for affiliate marketing, but I get nowhere because I didnt stick to one product and tried to get everything without enough skills.
Now I would like to stick to one product niche and work only on that for a while, to see results, my idea is to start my own yahoo store, to buy ready store designe and get a products to sell.
I have one huge problem, how can I get products to sell, for example power kites, where I can find some company who allows to sell their products on my site, and how does it happen do I get some affiliate code for product and whats happening next if someone order?
I know that I can finde few product in ebay or amazone, but how can I get someone who has these products all the time, not only one item like it is usually in ebay or amazone.
Can you answer on my questions, cause I have no clue with what to start.