There are several ways to execute other programs from within Perl, but as I assume you're running Windows (*.exe), you should use either system() or backticks. System just runs the program, backticks collect the output from the executed program.

system("netscape.exe") && die "Couldn't start netscape: $!\n";

$dir = `dir`;
[download]

There are other ways, like forking, but I think this is not possible on Win32 systems.