adding a sidebar photo?

[Timbow]

There is a plugin 'Simple Input Tabs' that will do what you want. It had some issues of conflicts with other plugins but if it's a simple site you should find it works well. Backup first.

Otherwise:
Copy template.php and rename to make a special template for your sidebar gallery pages.
In that template replace <?php get_component('sidebar'); ?> with <?php getPageContent('special'); ?> .
Make a page with the slug 'special' .
Then you can edit the special sidebar content as a page with the ckeditor, inserting thumbnail to image links or whatever.
You might want to configure the ckeditor to make it more useful.

HTH