When installing Tournamatch version 2.x for any version of phpBB, one of the first things you will want to do after installation is set the primary color scheme that Tournamatch uses. When using the software with PHP-Nuke, Tournamatch will automatically inherit the color scheme of the chosen template. The same behavior is not true for phpBB.
To set the main color scheme, find the Manage link under the Administration header in the top-most right block. Click this link and then navigate to the Manage Colors page under the Other section. Here you will find the three primary colors Tournamatch uses to style output. Each color is labeled and also has an option to make the color transparent.