PPC or Pay Per Click is exactly what it says.
You pay per each click that comes to your website. You will bid on a certain keyword (e.g. "Download TV Shows") - so when someone searches for that keyword, your ad will show up.
PPC campaigns are a brilliant way to send paid traffic to your hoplink. All major search engines will have a way for you to pay per click. Check the "Sponsored" sections, these are PPC ads that other people are paying for.
If you click one of these ads - then they will have to pay. This works on the basis that if you send enough visitors, one visitor will eventually buy the product and that product price (say $50) will be more than the price of the clicks (say $5).
Therefore the person returns a profit!
Affiliates! Bear in mind Google Adwords frowns upon Download products. You can try them by all means, however your best bet is Microsoft Adcenter or try one from this list below: They are all excellent alternatives and you can product great results!
www.overture.com
www.adbrite.com
www.Kanoodle.com
www.Findwhat.com
www.epilot.com
www.mygeek.com
www.pageseeker.com
www.bidclix.com
www.payperranking.com
www.Enhance.com
www.7search.com
www.Searchitfast.com
www.Search123.com
http://insite.lycos.com
www.splut.com
www.xuppa.com
www.brainfox.com
www.businessppc.com
www.espotting.com
www.pointcom.com
www.sabril.com
www.searchhound.com
www.goclick.com
www.LookSmart.com
www.hootingowl.com
www.hotways.com
Don't forget to test which ads are performing the best and then copy and slightly alter that ad - to find even better performing ads. Your CTR (Click-Through Ratio) will show you the number of clicks per number of searches that have been made.
The better the CTR - the more clicks you'll get!