Yes, you can manually install a theme.
Be sure to read the instructions provided by the theme author...
You may want to first use Bald Brick
suggestion as that way they easy to install and
way also gives you the option of modifying
the actual colours.
On the Scheme Tab
I've selected the Frothy Pink (gulp
) theme. See first screenshot
If you now choose the Colors Tab
(see next screenshot) it gives greater control over which colour you can apply to "individual" parts of a theme.
May want to experiment with a Theme you don't
want to use and it will give you an idea of how it works