File Format for Fortran-95

Hi

I have installed Xcode command line tools and gfortran package from HPC website.

Now, I can't figure what format should I use for input files to compiler.

When I used rtf and txt following error occured.......

ld: warning: ignoring file u.txt, file was built for unsupported file format ( 0x47 0x50 0x41 0x20 0x2d 0x2d 0x2d 0x20 0x31 0x30 0x a 0x47 0x52 0x45 0x20 0x2d ) which is not the architecture being linked (x86_64): u.txt

Undefined symbols for architecture x86_64:

"_main", referenced from:

implicit entry/start for main executable

ld: symbol(s) not found for architecture x86_64

collect2: error: ld returned 1 exit status

PLease Help....

Thanks

Gurpreet