When you have chosen your freebie, (by clicking on the image) you will be directed to Freebiejeebies.co.uk. Once signed up here you will be required to complete just ONE of their offers. Offers range from a Lovefilm.com FREE trial to paying a small deposit of £5-10 to an online gambling site (which you are not obliged to visit ever again). Once you have completed your offer the company you gave your business too will then pay Freebiejeebies for referring you to them. You then need to get a ceartin number of 'referrals' - people who follow you link to sign up to the freebie site. So Freebiejeebies is making its money from the offer company, and the offer company is making its money from the one time sign up, and advertising on their site. And the only way to get people like us to join up to that is to offer us incentives. Free incentives!
Here is a video that might explain it a bit better.
If you would like a further explanation ( I know I did!) then please have a look here. Exceem is an excellent website that will give you loads of helpful hints and tips on how to get free stuff.