Joining clickbank is free, just go over their website and register there. Then you need to browse the clickbank marketplace and research the type of products you want to promote. Let me know if you need anything.
Register your product on Clickbank first, that will cost you $50, as dropship said. After that, you will become Clickbank publisher and will be listed in the marketplace. You decide what % of sales you want to give to affiliates(up to 75%). So when, affiliate promote your product and make a sales, 75% of the sale will go to him, the rest is yours. You can change the commissions that you willing to pay to affiliates, but remember, higher commissions attract affiliates
Keep in mind there are other affiliates. I only mention this because it's an important consideration to choose the right one at the beginning because changing later is a pain. Lot's of times you lose 50% of your affiliates if you change. Do the products in the clickbank network fit with yours? I have noticed some products simply don't do well there because it doesn't reach their target audience. Lots of traffic doesn't mean squat if it's not the right traffic. I'd rather have less traffic if it's good targeted traffic.
You will want to promote your product in affiliate directories to gain affiliates. Just google search "affiliate directories" and you will find numerous ones.
If you're launching new products and need help with packaging them, getting them on CB/CJ/SR and others feel free to check my first sig. We help new merchants with all of the above and even do some recruiting for you... If you are interested in a JV from the ground up and have a great new product I'd be more than happy to see if I can help you. If there is interest and your product is a) relevant, b) not just another IM ebook c) ready for market please PM me with some info/brief etc. Cheers, NC.