To create database schema documentation do the following:
Goto the DatabaseDoc property page
Press New
Enter name in the first box ("project local" schema name), then enter Schema Name and Schema Identifier in the form (these three names you make up, and can be identical, the last one shouldn't contain any "special" characters like whitespace etc.). "Schema" is just a "namespace" for the tables, in case you want to have multiple databases, with overlapping table names, in the same T2H project
In the Documentation File edit, select where you want to store the databaseDoc file (full filename)
Select Database Driver
Fill in driver specific information
Press Sync Documentation File
After pressing Sync Documentation File you will be presented with a form asking you which tables you want to synchronize with your current databasedoc file.
The first time you may press All, then uncheck those you do not want. Later you can press Currently Documented Tables to only resync those you already have in your databasedoc file.