Bill,
Once you get the "manage attatchments" pop-up box, there will be a couple of choices:"upload file from your computer" and "upload file from an URL".
Since you want to upload from your computer that's the one you want. If you know the file name type it itno the box there. If not, click on the "browse button. Then , well, browse until you get to the file(s) you want to post. Select them and then click on "upload". If the photos are OK for size--and there is a message if they are not--you will then get a list of "current attatchments". Scroll down to the bottom of the box and click on "close this window". You will be back to your reply to post screen. And there will be a list of attatchments. You're set. One thing, if you "preview this post" the attatchments won't show up. But they are there. Click "submit reply" and you're done.
Rob
Edit: mc_vancouver shows you what the attatchment thing looks like! I don't type very fast.