theme wont load or preview (2nd attempt)

I tried to get some help on this before but did not solve the problem so i’m going to try again…
I select a theme but nothing shows up on the right window.
I get the left window that I can edit stuff in, but nothing on the right.
The preview doesn’t work even when i try the three default themes “twenty thirteen, fourteen, & fifteen”
Nothing will publish or become active on my site, it just stays on the “under construction” default page.
The instructions in the tutorial say:
“A live preview of any Theme (using your blog’s content) can be seen by clicking Live Preview.”
This step doesn’t happen…