Q: Prohibitory sign on started

MacBook Pro with Retina display, OS X Yosemite. On the start up Macbookpro is showing a circle with a line inside which is prohibitory sign. It goes no further. Tried but the disk utility.

Stuck with my OS X Utilities for couple of days. I tried the disk utility.  Finding the way out.

trying to do an internet recovery.

Then I come to a window for install OS X. my is is OS X Yosemite.

I click to continue. It varieties computers eligibility.

Then I click agree to go forward.

Then it says select the disc where you want to install OS X. it won't let me install.

What's that mean? And

Where is the problem?