Mac- from FAQ
What Are Attachments? The administrator may allow you to use the attachment feature of this forum, which gives you the ability to attach files of certain types to your posts. This could be an image, a text document, a zip file etc. There will be a limit to the file size of any attachments you make.
To attach a file to a new post, simply click the [Manage Attachments] button at the bottom of the post composition page, and locate the file that you want to attach from your local hard drive.
After posting, the image attachments may display a thumbnail, depending on the forum settings. To view the contents of the attachment (if it is not already displayed) simply click the filename link that appears next to the attachment icon.