my $filename = shift @ARGV;
unless ($filename) {
    print "Enter file name(s) to be backed up:\n";
    $filename = <STDIN>;
    chomp $filename;
}

if ( -e $filename ) {
    if ( -d "Backups") {
        # copy file to directory
    }
    else {
        mkdir "Backups";
        # copy file to directory
    }
}