Nibbler:
Checked for 404s in error log ?
Tried, but couldn't find how to do that with my host server.
snork13:
feel free to zip up what you have done and email it to me to try to fix.
Thanks! I think I'll take you up on that offer. I'm really enjoying trying to learn this as I go, but at the rate I'm going, I'll never get my gallery open to for business! What do I need to zip? Just my Kean theme folder correct?
TranznDance:
A link to your gallery might help.
OK. I will post that shortly. Haven't posted it because at this point, its purely in the test/learn stage and I know there's alot I have to work on before its ready for any reviewing. I'm kind of embarrassed to have the experts look at it.

KegOBeer:
Images in css are called relative to the css file location, and without quotation marks.
background-image: url(images/button_bg.gif);
I currently have it background-image: url("images/header_cell.jpg"); and its working. BUT...
On one hand, I was able to get the background image to show; on the other, I must have done a major bad somewhere, because now none of the themes will display except my style "kean", which started out as "reynolds". Any theme I choose from config displays as "kean", and when I go back to config, the drop-down box is back on "kean", like no matter which one I pick, it slips back to "kean". I planned on deleting all the extra styles at some point, since I don't plan on using anything except for my personalized style when its finished, but now I'm worried that even if I delete them all, I've still created a glitch in the pipes somewhere.
I'm going to list the steps I did and maybe someone can tell me where I went wrong and how to fix it.
From style guide-how-to:
Browse through the different themes that come with coppermine, choose the one you like best and start modifying it. To keep things simple, you should start with the default theme that comes with coppermine and modify it step-by-step On your local hard drive, copy the folder "default" (with all the files contained in it) within the themes folder and paste it to another location on your hard drive rename the copy of the default folder (do not use spaces or special chars), e.g. "my_theme" cut the new folder "my_theme" and paste it back into the "themes" of coppermine upload "my_theme" to your webserver . use a text editor and modify /coppermine/themes/my_theme/style.css Only change some bits within style.css at a time - save your changes and upload the modified file to your webserver, and view them in your browser
I did that as described, but not in that order. I think that's maybe where I went wrong.
I didn't find a theme close enough to what i wanted in the ones that came with the install, so I installed theme "reynolds" from this site. After installing it, I copied and renamed the original "reynolds" folder to "reynolds_orig" on my hard drive (so I had the orig in tact in case I had to start over), and was making all my changes to "reynolds", thinking I could rename it to my own name after I was done modifying.
I was making one small change at a time, then ftp'ing the updated style.css to my site, viewing, edit more, etc.. Then I hit this problem with the table background, and after the last reply here, I renamed theme folder "reynolds" to "kean", used find & replace to replace all occurences of "reynolds" within the documents of folder "kean" to "kean". Then I ftp'ed folder "kean" to the themes folder of my gallery, went to config, selected "kean" and presto - there's my modified theme,
and now the table back image is showing! Yeah! Only, now every theme I select displays as theme "kean". So I then deleted via ftp the theme folder "reynolds" from my server and replaced it with the original untouched "reynolds" folder I had saved/copied earlier. But it didn't help, becasue all my themes are still displaying as "kean".
So in fixing one problem, I have made a bigger one. If you're still reading, thankyou - I appreciate all the help.
Col