1. Click this link http://www.tremorgames.com/?ref=429440

2. After that, you need to register an account so click "Register" And fill the needed information.

3. When you're done, login and click "Tremor rewards" (There you can find what rewards you can buy by using your coins)

4. There is a category for each item example TF2 items, Bitcoins, CS:GO, Pc games (Origin, steam desura etc...), LoL (League Of Legends) and so on.

5. Choose your favorite category and find the item you want. Example: I want to buy a game called "Rust" so i click "Pc games and click "rust"

6. Check the price for your item. Example rust is 7495 Coins.

7. After that, you need to get the amount of coins your item costs. you can get coins by Completing surveys, watching videos, trading steam items for coins, downloading mobile applications (Ios & Android) or just simply Playing games (Completing achievements).

8. You can find Surveys, videos and mobile application surveys by clicking "Earn coins" 

9. After that, you can see 18 tabs so click any of them and start doing some offers. Example i click supersonic and complete a survey which gets me about 500 coins each survey.

10. When you have the required amount of coins for your item, go back to your item and click "Redeem"

11. Then you just need patience and wait up to 2-24 hours until your item has been sent to you via tremorgames message.
(They will send you a cd-key or game link for your item) 


All this just requires patience.
If you need proof that this site is legit, just simply google "Tremorgames reviews"
Also, Sorry for my bad english.