If you're running WordPress and are unsure of what theme you've got running at the moment, checking the theme can be done within the WordPress Admin panel.
Here's the step by step process for checking your WordPress theme:
The currently active theme will be highlighted to the top left of the row of themes available via your WordPress installation.
If you're wanting to check compatibility lists or verify your installation is up to date with the most current version, there are times you'll want to quickly check the theme version you're running currently.
Note: It's just above the theme author link and details of text.