Creating Own Incentive Site.?

I would like to make a few of my own incentive websites using my current CPA networks giving away "free" items to those who complete;

• 2 Bronze Offers
• 2 Silver Offers
• 6 Gold Offers

Obviously making the prize worth much less than the offers make me. (PM me for examples)

My problem,
I don't know how to make this legit.

Im guessing I need some sort of script to rotate the offers and keep track of what offers each visitor has completed, but I honestly don't know if I'm even starting off on the right foot.
Someone mind shedding some light on this for me or referring me to where I can learn more?
Thanks in advance for your time!

I have seen some different GPT Scripts I can purchase but they don't seem to work exactly like the incentive sites Im already promoting, but I feel like I am on the right track and would LOVE for some input.
Thanks guys!