How to get the dynamic options for selection field in PloneFormGen

[surendhar]

Hi All

I have installed PloneFormGen product
I have added "Form Folder"
Now I am trying to add selection field to that form folder
I want to get the options for the form field dynamically, to get the values I need to write python script, where do I need to write the script and how to call the script

Please any one can help me to solve this problem