If i join many affiliate such as cj.com, azooglesads, neverblueads, clickbank. Can I join many this affiliate but I have only one website ? please help me thanks for your information
Yes you can. They just ask your site address. In some cases they only approve your site on relevancy to their products.
Signing up for many sites is not a problem. Gives you a chance to see what each has to offer. But in the end, when it is time to get serious and start promoting product, work with a limited number of networks http://www.learntoearn101.net/2008/12/affiliate-marketing-mistakes.html
It'll depend on your site, but rank beginners tend to do best with ClickBank, I think. I'd recommend you not sign up to too many to begin with, but rather focus damn hard on selling a few products and doing that well. Scattering your focus across a bunch of different stuff can end up being costly. That reminds me of something: Chase two rabbits. Catch neither. - Japanese Proverb