Templates and structures I have decided to use Structures as a section type for a section of our site. Can anyone point me to some good documentation for this? 

In particular I have set up a structure and I have an _entry.html and an index.html file in a directory for the structure section. When I call the url domain.com/mystructure I am served a 404 error page instead of the index.html page.
If you haven't seen it already there is some good Docs on the Craft site on sections and how to use them.

Without seeing your Structure settings it is hard to pin-point exactly what the issue is here, but creating a Structure and adding your templates to it is a very easy procedure. I have attached a screenshot of a Structure for a project I am currently working on, so you can reference in case you have made a mistake somewhere.



So in my templates I have created a folder called services, and in there I have my index.twig and _entry.twig files. Try matching your Structure settings with the screenshot and see if that fixes your problems.