Selling 50$ Adword + 50$ YAHOO SM @ 20$ only(paypal)

I am selling $100 worth of PPC credit vouchers(50$ Adword+50$ YSM) @ 20$, if you need plz pm me, I will tell you my paypal id, when i recieved your payment, i will send voucher links to you.Thanx

Can you please give some more information on this? I'm new to this Google Adwords, and I really wanna know how this works?

As you know via Google Adwords you can display your ads on Google and its advertising network. Pay only if people click your ads.Your money will go to adsense publishers pocket as they are showing ur ad & Google ll get some percent of it as a middleman. So through this 50$ voucher your adword account will be credited 50$ and you can promote your site up to 50$.After that you have to fund ur Adword account again..,,same concept applies in case of Yahoo marketing too...