use strict;
use warnings;

use MyModule;  # load your module.

# call openFile.
my ($fh, $error) = MyModule::openFile('my/file/here.txt', 'READMODE' );

# Check results 
if ( $fh ) {
    # file opended ok, process file.
    # reading from a lexical handle works just like a global handle.
    while ( defined ( $foo = <$fh> ) ) {
        # do stuff
    }
}
else {
    # File did not open, show error.
    warn "Error opening file- $error\n";
}