I installed the free version (will buy Pro but can get the free working

Unix server , PHP 5.1.2 & Perl 5.008007
I installed like it suppose to be.
the cgi files and folders in the cgi-bin on the server (not in httpdocs)
I put the permissions on the folders and files.
So I think I did what I had to do but I'm always getting a 500 error.
My question is : is the cgi folder at the right place or should it be in my httpdocs like the others files of my website??
I'm new with cgi and stuff so maybe I didn't understand very well.
thanks
Didier