if file1 and file2 and file3 have values for file names then you probably want to use them rather than hard coding file1,file2 and file3. Like this:
Shell("C:\FORTRAN\TEST.EXE " & file1& " " & file2 & " " &file3, 1)

Better yet concat your command string first and then call SHELL:
dim cmd as string
cmd = "c:\fortran\test.exe " & file1& " " & file2 & " " &file3
shell(cmd,1)

That help?