How to change Gallery templates
Gallery themes can be downloaded from here:
Once you've downloaded the theme, you will need to upload it and unpack it under your /gallery2/themes folder.If you have downloaded a .zip file, you would need to unzip(extract) it and upload the unzipped folder that contains the theme to the /gallery2/themes folder. The folder that contains the theme will have the files "theme.inc" and "theme.css" in it.
Follow these steps to modify the theme:
Step 1 Login at your admin area by clicking on the Login button and filling up your admin login details.
Step 2 Click on [Site Admin].
Step 3 Click on [Display - Themes].
Step 4 Click on the [All Themes] tab and install the one you have just uploaded by clicking on the link.