Hi Rajendra,
It looks as though you might be following an older set of instructions.
Please retry using the up-to-date instructions at
http://github.com/railfrog/railfrogcms/tree/master
If you get "git is an unrecognised command" then you need to install Git
first - see the instructions. If you're using mSysGit, you'll probably
want to use Git Bash as your shell.
Note that the "git clone" command ends with "...railfrogcms.git", not
"...railfrogcms.gitk".
Make sure you delete anything left over from your previous installation.
Welcome!
Thomas.