I finally figured it out. Part of the problem is that when you finish editing a picture in Photoshop Elements, the program automatically saves it as a Photoshop file (psp) -- rather than a jpeg. It's easy to convert from psp to jpeg, but it does take a few keystrokes to do it.
I've posted quite a few pix already, over in the Ships forum. Many thanks to all who helped.
In case anybody's interested, here's the process:
1. Edit the pictures in the Photoshop Elements Editor, and save them in the Photoshop Elements Organizer. The Editor will want to save them as Photoshop (PSP) files, but when you click "save" it will give you the choice to save them as jpegs. Do so.
2. Still in the Photoshop Elements Organizer, create an "album" and put the photos you want to post in it.
3. Drag and drop the photos you want to post from the organizer to some empty space on the monitor screen. (On mine, there's a little room at the bottom, at each end of the app dock.)
4. Open your browser and go to the Photobucket homepage. Click "Upload."
5. Drag and drop the photos you docked on the monitor screen into your Photobucket "library."
6. Pick one of the photos and left click on it. A box will appear that says, among other choices, "Copy URL." Click on that option.
7. Go the the FSM Forum page and open a new post. Click on "Insert Image," then right click, then left click on "Paste." The photo will appear in the post.
I suspect there's a faster way to do it, but that's the one I figured out - and it works. Now that I have a little practice I can post a photo in less than a minuted.