Each theme has a set of available parameters that allow you to customize the colors, thumbnail size and many other aspects of the generated gallery.
However if those parameters are not enough and you'd like to make the galleries to match your website design, then you can make changes either in the generated pages or in the template files that are used to generate the album.
Template files can be customized with easy if you are familiar with the HTML markup language. The files are located in the "C:\My PhotoAlbums\Templates\" folder (depends on the installation).
Please refer to the Theme Development Manual for more details and information about the theme customization.
Anyway, please feel free to ask any questions that are not covered in the documentation in our Themes Questions and Answers online forum.