Hi all. You need to upload your pic to a host site like http://photobucket.com/ its free storage. Once you've joined and uploaded a pic you'll see the url of the pic http: // photobucket.com/yourname/pic.jpg for instance. All you do is copy that url and in the reply to a post here you see insert image picture. Click that and paste the url in.
Or you can use the shortcut by placing [IMG] in front of the url and [/IMG] at the end of it.

thanks

I assume you use the same method for uploading your own avatar and signature pics?

Avatar can be uploaded from your computer. Signature needs to be hosted unless its just typing. My sig is typing only.