Before launching your site you can try out as many different templates/themes as you would like. Generating a new site template is done right from within your the software account.
1. Settings
2. Click "WordPress" or just go straight to this link
If "WordPress" settings is grayed out, see here
3. "Add WordPress" Button
4. Leave Option as "Generate New Site"
5. Fill out "Website URL" with your eventual web address it will be launched on
6. Select Theme
7. "Save & Close" button
Following those steps your new site will be generated, within 5-15 minutes you will receive an email notifying you that it has been created and instructions on how to move forward.