Not for the Faint of Heart…
In order to customize a Web Photo Gallery template, you'll have to open the HTML pages and make the changes there. If you've never worked with any Web authoring tools, I'll get my warning out of the way right now and tell you to be careful! The best plan is to find and copy the folder that contains the Web style you want to customize.
You'll find the Web templates in Hard Drive: Applications:Photoshop CS2:Presets:Web Photo Gallery on a Mac or C:\Program Files\ Adobe\Adobe Photoshop CS2\Presets\Web Photo Gallery on a PC.
Duplicate the entire folder within the same Presets folder location so that your copy will appear in the Web Photo Gallery dialog.
To make changes to the template, you'll need to use a Web authoring tool, such as Dreamweaver or Adobe GoLive, or a text editor. Here I opened the file called FrameSet in GoLive (depending on the template, the main page may be named slightly differently). I added a small logo and saved the fileit's important that you keep the same name and save it in the same location.
Then I ran the Web Photo Gallery again, this time choosing my newly edited copy of the template.
You can also edit (again, with caution) something called tokens, which determine the size and position of information, such as the site name. (For more information on customizing the gallery and tokens, look in the Adobe Help Center, searching "web gallery.") Tokens always display with "%" at the beginning and end of the name, such as %PHOTOGRAPHER%.
Here I moved the %PHOTOGRAPHER% token above the %HEADER% token and made it larger.
The result of running the Web Photo Gallery again is shown here.
In this case, I also changed the background color of the page in GoLive.
In case you didn't get the message about customizing Web Photo Gallery templates, let me say it again: Use extreme caution and make sure you're working on a copy of an existing template.