A complete answer to your question may be found in perldoc perlipc. However, a brief synopsis would look something like this (taken almost directly from perlipc):

use POSIX ":sys_wait_h";
sub REAPER {
  my $child;
  while ($child = waitpid(-1,WNOHANG)) {
    $Kid_Status{$child} = $?;
  }
  $SIG{CHLD} = \&REAPER;  # still loathe sysV
}
$SIG{CHLD} = \&REAPER;

..............

for (1..6) {
  do {
    $pid = fork();
    unless (defined $pid) {
      warn "cannot fork: $!";
      sleep 10;
    }
  } until defined $pid;

  if ($pid) {  # parent
    print "forked process $pid\n";
  } 
  else {     # child
    my_sub(@parms);
    exit;  # don't forget this
  }
}
[download]

Untested. Have fun.

*Woof*