I have a good website idea! How do I make this sort of website when I'm 16 years old?

It would seem that any advertising revenue system could be adapted to route the revenue too charities. There would be a better chance of initial success if it didn't rely on the advertisers only using your site or even their having to be aware of the charity slant. This way, a standard ad network that pays sites for viewers could be used. Ultimately this plan could fail because the value of passive ad views is too low, commonly ads are sold at a Cost Per 1000 (CPM) basis. prices vary considerably, but earning $5 per 1000 views would be pretty good, that would amount to a 1/2 cent donation per view, probably not a motivating factor. Your plan shares some features with Pay To Click (PTC) schemes which pays the users some 4 cents a click. Another ad revenue sharing site, Clickbank, kick back part of the bounty they receive from advertisers for your participating in various marketing schemes, users earn some fraction of the ad revenue the site and various middlemen earn from the merchant, if a charity got paid instead of the user it might be earning perhaps 20% of the merchants ad cost. Those charities who put their name on car donation programs earn just a couple of dollars per car, the business doing the promotion gets the lion's share, some of your good will clothing donations end up being sold as rag scrap for 4 cents a pound. You might review the model these various Ad Revenue sharing sites use, you should be able to just add the user/contributor payment to charity option and perhaps lower the hose cut. Odds you would need an 18 year old to be a legal proxy where money changes hands. You would need to have a registered non profit for credibility.