Have you gone through http://learn.wordpress.com yet? As well, check out the demo for that particular theme. I believe each premium theme comes with staff support in the Themes forum, so you can look there as well.
Part of what you purchased is support direct from the theme’s designer. The person with the username account who purchased the theme can post to the Premium Theme Support forum for the theme to get help with it in the Premium Theme Support forum. http://premium-themes.forums.wordpress.com/forum/the-writer