can someone explain a thing about affiliate for me

sorry i am usually busy with some other niche business, so never had time to figure out what is was, my question is

if i registered for affiliate websites, does it mean i build an interesting website/blog/facebook page with advertisement that links to the affiliate websites? or do i build a website with interesting products that link to the affiliate websites?

not really clear to me

If you register for affiliate website; that means, you can now promote their products.
Now there are many methods to promote affiliate products, like:
making a website and ranking the same
Creating email list
directly promoting products through YouTube....etc.
You can choose any method which suits you the best!
Search the forum; you will find a lot of new methods too

Hope that helps