If youa re talking about in the signature, you have to upload an image (not very big. Large pics in sigs are annoying

). if you are talking about an avatar, you have to make a picture on your hard drive, shrink the size down to 80 x 80 or less (I think) and not over 10kb in size (I think again. Been a while since I uploaded my mugshot)
Click "Upload Images" in the light blue bar at the top of the page, and find the pic in your files that you want to uplload. Then once you get file uploaded successfully, copy the http address it gives you
http;//www.simviation.com/yabbuploads/yourpic.jpg. Remember the name that you gave the image on your PC such as "SaVas.jpg"
Then if in your signature click the insert image in the "Add YABBC tags"
Remove the letters URL between the tags and insert the
http://www.simviation.com/yabbuploads/yourpic.jpg between them.
Then where it says "yourpic" in the http address replace that with the name you orig gave the image such as my example above so it would be
http://www.simviation.com/yabbuploads/SaVas.jpg
So it will look like [img}http;//www.simviation.com/yabbuploads/SaVas.jpg{/img]
(NOTE: both ['s replaced with { so as to not make an actual image)
Then save your profile
Good luck.
---Stephen