If you are asking about profile customization, you need to upload picture to your album first. Then you open your profile, there is a button on top "Customize my Profile". Click on that. You can then use pictures as headers etc.
Well bro, it is advisable not to post such things in market place. Posting "nice phone" or "nice bro" will lead to the posts getting removed. So be careful in the future and PM the thread maker if you want to buy/reserve something.