Lino is poorly documented. The Developer's Guide is far from being complete. Lino is a big project, but we are a small community and have limited resources for writing documentation.
On the other hand, the Lino project decidedly wants to be well documented. We use Sphinx, the best and most powerful documentation system available for Python projects. We want the Lino documentation to remain free.
Keep in mind that Lino belongs to us all because it is free software and you can help us with the documentation right now by asking questions when you get stuck. Your questions are important feedback, and already your work of formulating them is a contribution for making Lino better. Thanks in advance.
Working on free software implies that you also use the source code. A few guidelines for under your pillow:
Inspect the examples and read the code.
Don't hesitate changing the source code and see what it does.
When you get error messages, don't try to "just get rid of them", rather understand what they mean and learn from them.
Read Hamza's tutorial Discovering Lino using your debugger.
Read Steven Kryskalla's Advanced Python Debugging with pdb.