Dear ikegami, ccn and Random_Walk,
Thank you very much for helping me. I tried these three things and they all worked:

`mkdir C:\\Windows\\Temp\\myfolder`;

my $folder="C:\\Windows\\Temp\\myfolder";
my $cmd=`mkdir $folder`;

my $folder="C:\\Windows\\Temp\\myfolder2";
mkdir "$folder", 0755 or warn "Cannot make directory: $!\n";

I really appreciate your help! I guess I got myself confused by the slashes!
Best regards,
shn4002