Merging my chapters into one document

How do I merge all my text chapters into one document please?

Select the items you wish to merge, in the Binder, and press Cmd-Opt-M. But do note, it is rare that you actually need to do this. Take a look at the Edit Scrivenings feature and see if temporarily merging things might do what you want. With that you can make everything look like a single document (with handy alternating background colour to indicate boundaries between items) and when you dismiss it all of your edits will have been made to the source documents, while typing. In the end, Compile will also merge everything into a single output document you can import into a word processor. So for the most part, physically merging binder items together is unnecessary.

Yes, I would imagine you want Compile Draft - in which case I definitely recommend the tutorial and Help file, as this is a fundamental feature of Scrivener.
All the best,

KB and Amber V

Many thanks