upload it to tinypic.com
copy the direct link
[*img](inster direct link[*/img]
take out the *s
Or alternatively get a photobucket account eh? It's what I use for all my picture. Multiple pictures uploaded at the same time, it keeps all of them on your page so you can link them again if you wish and to top it all off, it has a box under the picture that is already set for forum pictures (already has the {img} tags) so you just copy/paste it.
SAMPLE:
[*IMG]http://i483.photobucket.com/albums/rr200/jminnix/LOLWUT.jpg[/IMG*]
or
c/p'd from photobucket, took two seconds.