Here you define common settings for the system.
You will find an explanation for every field beside the field. So here are just some special comments:

Basics

Custom forms:

you can create custom subforms named (ynDK_subForm_<yourname>) with which you can provide your own fields to editors. To declare your custom forms you have to fill in their names in this field. Use only <yourname>, spare the '(ynDK_subForm' part.

Web editor

You can declare a stylesheet to use in the fckeditor here.

Caching

You can switch the caching off here while you're developing the site. That makes it easier to test design modifications.
But if you plan to go into production, you have to switch the cache on again. Without caching it's most likely that your Domino server crashes sometimes because of too many open handles.

Custom configuration

You can include your own fields here when you implement the (ynDK_dbconfig) subform. You can access these fields by using @getProfileField('DBConfig'; '<your field name>').
Make sure you always use a 'c' as prefix for your own fields.