If you want to have access to the DB parameters when you define a slave site, you need to define a JMS templates rule where you will specify the replication rule.
In the "manage site", you will select the "template site" that describe the website that must be replicate.
You can only have the access to the DB parameter when you have something to replicated.
Otherwise, this let you create a fresh slave site
See tutorial video 9 that show you how to create a fresh slave site.
If you want to replicate website, you can be inspired from the tutorial video 13, 16, CP-05
www.jms2win.com/tutorial