The Portrait Image on AmericasTAKEN.com is similar to a Facebook profile image. It appears on your profile in the same place it would on a Facebook profile.
You may want to change your portrait or the portrait(s) of your TAKEN Child(ren) especially you didn't upload one when you created the account or you used one of the stock icons from the gallery. Portraits could be instrumental in your TAKEN Child finding you someday so you want a nice, clear image showing your face as your portrait picture.
The main menu is in the upper right corner of the screen.
Edit Profile is under the My Profile main menu option.