I think PSP hates you GCstyle.
I'm going to go step by step, ok?
1. Open the GIF file (I'm using attempt #2)
2. Open the GIF Optimizer. If you don't see it, go to view > toolbars > select "Web Toolbar".
3. Click on the colored box that is next to "Areas that match this color". When you hover over it, your mouse icon should change to a pipette.
4. Choose R:255 G:255 B:255 (white) in the bottom right corner. That is the color I want to change to a transparency. Click OK.
5. Notice, back at the GIF optimizer, that in the second preview window, the white background of the picture changed to a checkerboard pattern. That represents a transparency.
6. Click on the "Color" tab.
7. Under "What method of color selection do you want to use?", select "Existing Palette". Click OK.
8. Now PSP asks you to save the file. Save it as a different name the the original picture, so you don't mess up the original. Click Save.
9. Now, PSP is only showing the ORIGINAL GIF, since you haven't opened the transparent GIF, you just saved a copy of the original as a transparent one. Open the transparent GIF you just created.
10. You're finished! Upload it and try it out.