This does not belong here, this is where you get help on how to install and play the game, and having a forum avatar doesn't count.
But since I pity your lack of common sense, I will tell you, click on the profile button, and on the left under "modify profile" you click on "forum profile information", then you click on the "I will upload my own picture" button, then go to the "browse" button, and search for the picture you want there in your computer files, once you have opened that picture, you scroll down to the "change profile" button, and click it.