There is a user manual for Gaia GPS available in both the iOS and Android apps under Settings > Help > User Manual and Support. This, along with the Help Center articles is the best place to look for up-to-date info on how to use Gaia GPS.
That being said, there may be times when you would prefer to download a PDF manual for printing or referencing offline. These can be accessed via the following links:
Note: The PDF manuals are updated frequently to reflect changes in the apps, so make sure to return here for a new version from time to time.