Try putting it in your cgi-bin directory.
A CGI is basically a program that runs on the server - it could do anything it's coded to do. So, to help with security, most servers require CGIs to be placed in a special directory (cgi-bin), where CGI execution is permitted: it's easier to ensure good security on one directory than the entire server. Without this, if you accidentally set a directory to be world-writable, someone malicious could put a file in that directory and then execute it via CGI, potentially deleting everything on the server. PHP runs in a sort of sandbox, so it's not such a big issue.
I had pretty bad experience ealier but on frihost it works prefect .. just put your PL files in cgi-bin and if chmod them 777(suggested) or 755.
No, 777 is a bad idea: 7 means rwx ie read, write and execute. You only want yourself to be able to write to your script files, so set 5 for group and world permission (r-x), making a total of 755.
Yes, the permissions are as follows:
You add them together to get the permission you want, then you put three added values after each other to give owner, group and world permissions, in that order. So 755 is rwx for owner, and r-x for group and world.
You can also add some other numbers at the beginning for setuid, setgid and sticky (can't be deleted), but I've never used these. HTH.