Go to ur User CP (either via "Quick Links" or "User CP" just underneath where u see the thread title etc...
Once there on the left there should be a column with one of the options being "Edit Avatar". Click on that and then if ur avatar is a picture from a website then copy the link and paste it in the first box. If the picture's saved on ur computer then click browse and find the file and then insert that.
then just press "Save Changes" and u should be done.
hope that helps...
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