That question is a bit vague, odds are your talking about internet affiliate marketing, which is one of those businesses with a low cost of admission but a high rate of failure, don't invest your rent money.

One popular hangout for affiliate marketing rookies is warriorforum.com, there;s a section of cheap member authored tutorials good enough to get one started.

The safest approach is to build one or more magazine like web site that you build up over time to attract thousands of visitors a month, mostly from search engines, this 'free' traffic can be marketed to along with making you revenue from selling ad space.

I have some affiliate business ebooks in pdf format. I can email it to you if you like. Just give your email adress.