cousinp, firstly, I am not a Windows user ....
But it really looks like there is a problem with your input file, myforstObjPas.pas. Please, from the same place you ran that fpc command, you could type "dir <enter>" so we can see what the file looks like ? Obviously, it must be present there, readable by you, not zero length.
You would not get that error message if it contained invalid pascal code, the error would be more explicit.
Just run that dir command, copy and paste the result into a message here. I am sure all will be revealed then.
Davo