I'm trying to put up technical documentation for the apps I'm creating and maintaining.
The audience for these are the technical people on the project (troubleshooters, DB, programmers).
The docs don't need to go in real tech detail but must make the apps more understandable tech point of view to people involved in the project. What's happening and why and where is it happening.

I know I can put up data flows, processflows, class docs using UML etc...

But I don't really know where or how to start or which guidelines to follow.
Which sections should there be in a tech doc, or how to describe the items.

Any guidance on this would be highly appreciated.
Bookreferences, URL's, experiences.....

Thanks in advance.