Stop double posting, and provide complete information before someone can help you...
Like it has already been said, for you to use an image as an avatar or a profile picture - the image must be maximum 100x100 pixels in dimension and maximum 10KB in size. Without this, the forum will not accept your image...
Please host the image you are trying to use and post it in this thread, so that I/someone else can tell you what is exactly wrong with it.