Welcome to VZi
When you hit 'New Thread' or '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', 'Reply' or 'Quote'.
Try it now, by clicking 'post reply' and following the above ^.