I’ve been trying for a long time to put the three columns, as it appears in the preview of the theme, and I’m not capable. It’s just one.
I’ve read the chat and you have two problems: not to be premium (or something similar) or not to have it in wordpress.com . In my case I do both. Besides, you say that there must be content or you send the instructions of the page (I’ve also done it and it doesn’t work).