You can see Lite Bright listed here on the plugins page. It doesn't come with Tools.
Open a *.html file with "File > Open". This will come in handy as you change colors later on. In the Colorizer Manager ("View > Code Colorizer > Styles > Edit..." menu option):
- Select "hkThemeDark1" on the left, which is what you're wanting with some modifications
- Click the "Duplicate" button to create a new colorizer based on "hkThemeDark1"
- Type in a name for your theme ("MyColorTheme" in this example)
- Click "OK" and you'll see "MyColorTheme" added to the list of colorizers
i = item, n = name, b = background, f = foreground, s = style (s='B' adds bold, I adds italic)
Now you can modify "MyColorTheme" to your liking. They're HTML color codes, so for example change 'tag' color to red with f='#ff0000' Then click the "Apply" button to test your theme, with the help of *.html file you opened earlier.
Hope this helps! Feel free to post any questions that come up, preferably with screenshots.