Welcome to PEEL, snot
To get pictures in there you need to use UBB-codes, these codes are used to format your text as well, like bold underlined and italic and such.
these codes are explained in the
PEELers' FAQ. Many other useful stuff - along rules and other explanations - is in there as well.
in short: the tags for images are [IMG]http://xxx.xxx.xx/xxx...[/IMG]
Be sure that you picture is available on the internet. And not just on your computer. That means that you have to upload it to some place that hosts it for you. For pictures there are quite a lot around.
Imageshack.us is just one of them.
after all... enjoy your stay here.