Shell script in File sender CC

Hi,

I want to use a shell script in the file sender CC before processing section.

The script will be used to add a prefix (i.e. "SubDivision_") in the files located in a ftp path and then it will be picked using Sender CC as SubVivision*.

This is first time I am using shell script.

Is there any step by step document for this. I had some doubt -

1) where the script should put. In FTP or in PI server . If in PI server then what should be the path.

2) what is the format to put the script in CC with path details.

3) Any additional configuration is required for this .

Please help.