lol
here,
http://imageshack.us/ you don't have to register for this one.
go there, upload a pic, use that link they provide, either hit the "insert link" button or the "insert image" when you post and volla
Ok, you have to get your picture from your computer onto the internet first, photobucket is an image hosting site where you can have links to your picture, but first you have to upload them there.