I want a facebook ad voucher. Help?

I'm looking for someone [trustworthy] to provide an ad voucher. I have NEVER used facebook ads, and want to use it on a personal page. So a few DUMB questions haha:

1) What are the best prices to pay for ($50 or $100) vouchers?
2) How to use them- do you just present the code at checkout w/ paypal?

Hey,
Also need a fb voucher
thks