You set the number of posts you want to appear on the front page of your blog on this page > Settings > Reading
Blog pages show at most __posts
However, Staff have been introducing "infinite" scroll to themes -- a site wide change. http://en.forums.wordpress.com/topic/to-infinity?replies=137
You have a premium theme and read-access to the premium themes forum is now open to all users so you can search to see if your question has been previously asked and answered there. The premium theme forums are at http://premium-themes.forums.wordpress.com/ with separate sections for each theme.
If you are not successful when searching there is a link for the specific Premium Theme support forum for your theme under Appearance -> Themes in your blog’s Dashboard, but do note that the premium theme must be active and you must be signed in as the user who purchased it in order to see it and post to it.