You can add an image to your profile that will appear in the discussions if you would like to. To do this, click on the arrow next to your name image, in the top right-hand corner of the screen. From there, you can edit. your profile.
Please don't use a real photo of yourself. Instead, please use an avatar. You might have one already that you use on other websites, but if you don't, here are some options that you can choose from.
Simply right click and choose 'Save as...' on the avatar that you want to use, and then upload it to your profile.