Type the right version of this for your system:
C:\path\to\R\bin\R
That full path can be gotten from the installation location of R, or just from the R shortcut. On my machine by right-click - Properties (right click the shortcut within the task bar item on Win 7) and in Target on my machine is:
C:\inst\R\R\bin\x64\Rgui.exe
So, for me it is
C:\inst\R\R\bin\x64\R
or
C:\inst\R\R\bin\i386\R
or even more generally for current and older versions
C:\inst\R\R\bin\R
to start R.
I tend to always install R to this location, so I put my most used location (bin/x64) in my Path and I can type "R" from anywhere.
The Path on Windows is a semi-colon separated list of directories modified with Properties on My Computer under Advanced (System Settings), Environment Variables and within System or User variables.
