I realize there's very minimal documentation (well, actually none), but I'm hoping to correct that very soon (I'm writing up some documentation over the holiday season for release soon!).
Anyway, feel free to ask questions here and I'd be happy to help (and I'm sure some of the other users who hang around this fourm are happy to help as well).
I think your question is regarding how you would set up your SQL queries if you can't access the SQL DB directly. At the moment, you need to know the structure of the database in order to build queries (for example, I recommend having a local copy with fake data to write your queries on). However, one of the long-term feature goals is to add a Query Builder that will let you select Tables and Columns using a graphical interface, so you don't even need to write queries.
If you need help writing queries against the built-in DNN tables, I can do my best to help. If you are writing against custom tables, I'll need more information about their structure to help out.
Thanks for your interest! Hope we can help out here.