I'm trying to activate attachments as well.

I'm not sure I know what I'm doing. I've created a new directory named attachment under forums. Now what? I thought that by inputting /forums/attachment/ in the "Attachment Storage Directdory" field that it would work. But that has failed. Don't know what to do.

I also noticed that when I uploaded a file, it added a "1-"

Very confusing. Please help.

You'll need to enter the full path, what you can do is look at the DB, Paths & URLs section of the control panel to get an idea of what the full path is. The number that you see on the filename is so that there are no conflicts if 2 people upload a file with the same name.

OK, after much trial and error, it finally worked.

I'm a little confused though, and perhaps it's because I'm using a Mac, but what then would be the difference between simply linking to a .pdf file and "uploading" a .pdf file.

In the attachment feature, I was hoping users would be able to click on something and that something would load to their desktops. But after playing around with the attachment feature, I don't see a difference between linking to a URL and clicking on the "attachment."

Hope that makes sense.

Well, linking would generally be done off-site, and attaching would be uploading to your server.

I've added a small guide to attachments here