I misunderstood part of your question.
Yep, if you want to change your Theme, get a new theme. Look at Options > Themes. More info about 8800 themes in two sticky notes at the top of this 8800 Forum.
As well, if you do nothing else today, go read the Tip sheet located here. It will improve your health and brighten your teeth:
Stinsonddog's Blackberry Tips <---click here