How to modify the description

Hi I'm new to webgrab+ and need some bginners help:

I'm trying to get some more data into the description.

As far I got it to work to "add" data at the end e.g.:

                     description.modify {addend('category' not"")|\n /Category: 'category'}

1.) Is there a command / possibility to insert data at the beginning instead to add at the end??

2.) Is there some kind of general repository of commands with syntax?

Thanks for the help in advance