To send a pic in the pm, post your pic in pastebin. Within the messanger, select the insert image button. You will find a toolbar asking for the adress. In pastebin, right click on the picture and pick Properties. You will se 2 tabs, one giving the adress, the other giving the URL. Copy and past both into the toolbar.
Note that jpg works best in pastebin.
EDIT: Yeah, ya need to use Imageshack.