I'm admittedly quite the newbie with XOOPS. However, I have one simple question, even though I'm fairly familiar with php/css: Where do I put background images? I'd like to add background images to my main page, as well as to the 'join us' page (two images here actually, one under each heading), but I cannot find where to put the code.
Can someone please point me in the right direction? Thank you.

First you need to find out which theme you are using, properly you are using the default theme, so put your images to xoopsInstallDir/themes/default/ directory then modify the theme.html or style.css file to include you images. However as I know, your image will appear on every page if you put it to theme.html, but don't count me on, I am newbie also.

Depending on which module you open with you could edit the corresponding template for module or create a custom intro center block. the registration page does not come with a template so not sure where to edit this other than register.php

Take a look at this FAQ https://xoops.org/modules/smartfaq/faq.php?faqid=267

Thank you, everyone, for all your input...but please let me add to what I previously posted:

We do not start with any specific module---we don't want to since we'd like to have an image on the main page rather than any of the modules appearing there. Right now, this is what the main page looks like:

Clan Mac Simoin

This the other page where we'd like to have two images, one under each heading:

Clan Mac Simoin Join Us
(I realize that the application link doesn't lead to one...it doesn't just yet)

As for theme style, we're using the "phpBB Style" (we like its simple, clean look). I know where my images go, but which theme.html needs to be changed to include the images (path)?

/themes/theme.html?

/phpbbstyle/theme.html?

Or does one of the many index.html's need to be edited?

As far as creating images in blocks---for some reason, I cannot get the image to show, even though I've tried using different paths in the code listed with how to do this.
How should the code look if the image is in the images folder for the theme we're using? Did I put the image in the wrong folder?

We'd really like to get this done ASAP---getting the website finished is just one of the issues we're trying to resolve as quickly as possible---and though XOOPS was by far the best of any OS content management system we could find, we're decidedly new to XOOPS and need a little more help than we anticipated.

Thank you again for all your help.

I've managed to get an image on my main page but now have 2 problems:

1. The image only shows if a user is logged in.

2. If I try to center the image, it repeats below the footer. (obviously, it's in the wrong place in the theme.html)

Can someone please help me fix this? Thank you.