There are a couple of different approaches to choosing a WordPress theme:
1. Try to find a theme that looks just how you want it straight out of the box (or with a few small tweaks). Then just add your own text and images
2. Choose a plain looking, but flexible, theme as a starting point and customise it to look just as you want it to.
I favour the 2nd approach, but that doesn’t mean it’s right for everyone.