Oh, here, let me try to help out there.
Unfortunately, it looks as if you attempted to load straight from your computer. Sadly, don't think that can be done (unless its for an avatar or banner)
That said, a site like
photobucket.com makes it really, really simple for you to first get your photo onto the internet. You'll have to set up an account, but once that's done its a pretty easy site to pick up on.
Then, after getting your picture uploaded to a site like photobucket, you just right-click over it and select "copy image location". The information copied will be exactly what you need when you click the little
/"insert image" button on a posts options on this site. (where the button is right above where you type to actually add your text)
If you have any questions on any of this, of course, don't hesitate to just let us know!
side-note: The same "right-click" / "copy image location" over your photo into the posts
/"insert image" process can also be done with any image you see anywhere on the internet too - you don't only have to do your pics! (just be careful with copy-written images!)