If you like simple, then where you would code:

#! perl -slw
use strict;

#...

my $output1 = `somecommand`;
my $output2 = `someothercommand`;

#...

print for $output1, $output2;
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Do:

#! perl -slw
use strict;
use threads;

#...

my $t1 = async{ `perl -e"print, sleep 1 for 1 ..10"` };
my $t2 = async{ `perl -le"print, sleep 1 for 'a'..'z'"` };

#...

my $output1 = $t1->join;
my $output2 = $t2->join;

print for $output1, $output2;
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(Note:The second snippet is an actual working example!)

And er...that's it really. It requires a little more if you have lots of commands to run and reason to limit the level of concurrency. But not much.