Ok try this just to get the hang of it without those pesky quotes messing things up!
On the lower right of every post is a Reply button, clicking this will include that post as a quote in your reply. Don't do it! - there's no need for that.
Go to the base of the page and you'll see another Reply button (slightly larger), click that, you now have a blank-slate to reply in, good.
Now type something,
add a carriage-return or two,
click the Upload File button and choose your jpg,
once uploaded choose the embed image icon by the newly attached jpg,
it'll embed as a text-based link,
add a carriage-return or two,
type something.
Preview it.
Post reply.
Let me know if that helps!
