Google Adwords can be used to drive targeted traffic to a sales page. You simply make an ad in your adwords account then use your affiliate link in the target page URL of the ad. Obviously, you will have to continuously measure the conversions and see if the campaign cost is less than the campaign profit in order to keep the campaign running but I am sure you get the idea.
An affiliate agreement is when a company or an individual agrees to pay you for successful referrals. For example, Amazon has a massive affiliates program where they pay you a percentage of the sales you generate using their affiliate links. Affiliate marketing is everywhere these days. In fact, we’re able to offer our own Blogging Mentorship Program for free because Bluehost sends us money for every customer we refer.