I think what you're looking for is in the Perl FAQ:

How do I start a process in the background?

Several modules can start other processes that do not lock your Perl program. You can use IPC::Open3, Parallel::Jobs, IPC::Run, and some of the POE modules. See CPAN for more details.

You could also use

system("cmd &")
[download]

or you could use fork as documented in "fork" in perlfunc, with further examples in perlipc.