While the SB manual is simple this is largely by design, as the features of individual vehicles differ - some because of different functionality of the prototype vehicles, and some because of more advanced features added since the first releases, not all of which have been added to the existing catalogue yet.
The wiki:
http://www.steelbeasts.com/sbwiki/index.php/Main_Page
has a lot of useful information already, and more is being added.
More or less detailed information is provided for the operation of the M1A1(HA), Leopard 1A5DK, Leopard 2A4 and Leopard 2A5DK. Other pages detail the creation of terrain maps, mission creation, battle planning and tactics etc.
In addition the tutorials are fairly thorough, and you should be able to operate a vehicle or platoon after following the complete set for a single type. The briefing notes remain available from the map screen btw, by selecting the 'briefing' radio button on the right pane.