cannot compile a.f


I just download the PGI Community Edition for Windows 10 from ( and Windows 10 SDK and Visual Studio Community 2015. But when I tried to compile a simplest Fortran code (type a.f (fixed form)), it kept give me following massage:

PGI Community Edition 18.4
PGI$ pgfortran a.f
PGF90-F-0002-Unable to open source input file: a.f
PGF90/x86-64 Windows 18.4-0: compilation aborted

And this is the only error massage. I do not know how do it.
And would you tell me How do i change directry.

Thank you to help me out.