Some of you newbies (and some oldies) seem to miss this bit . . . so . . .
When you hit 'New Thread' or 'Post Reply' (if you're already in a thread) below the box where you type your reply, there's a 'Manage Attachments' hotlink. If you click that you'll get a pop up window where you can upload 4 images/files from your PC in each post. If you need more than 4, just hit reply again after your post and add another 4. It'll all make sense if you click on 'Manage Attachments'.
(It doesn't work with 'Quick Reply' tho' . . . only 'New Thread', 'Post Reply' or 'Quote'.
Or . . . you can link pics from your Photobucket/Flicker/etc. account or any pic that's hosted on the net, eg FaceBook, Ebay etc. by following these instructions:
Pics make for better ads.