@M R L
its simple bro
Go to  User Control Panel>Edit Profile>Edit Signature then
you can see your current signature in the form of text,,.
now place curser where  u want to add Picture,,
\Click on Img  Button on Top,  it ll b like   this   a
and Copy image URL  here   <>                [img]<>[/img]
Ur picture should not over 150 * 150 pixels
then click Ok  
