Question : paypal withdrawl

i am making a simple affiliate system. i want to give control to affiliates so that they can withdraw money when ever they want.i want something like this

1) click on withdraw money
2) enter paypal email
3) withdraw any amount they want (ofcourse in limit so that their balance doesn't go negative)

thanks in advance

Answer : paypal withdrawl

"how do sites like odesk pay people via paypal?"

I do not know ODesk, but I know a bit about PayPal.  You can SEND money, and there is an automated interface that will let you do that.  But you cannot TAKE money from any account but your own.

Using PayPal is a professional specialty and it may take months to learn all you need to know, so here are some learning resources to help you get started:

https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&content_ID=developer/community_overview
https://www.x.com/index.jspa
https://www.x.com/community/ppx/documentation
https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&content_ID=developer/library_download_sdks

I wish it were quick and easy to learn all you need to know, but it's not - PayPal is the leader in so many areas of online commerce that it is always under attack.  As a result, it is constantly growing and changing.  PayPal developers, of necessity, spend a lot of time just keeping up with the technology!

Best of luck with your project, ~Ray