After loading the template or style file, you can pretty much continue using MuseScore as you already were. However, in order to get the most out of the templates' default settings, here are a few things worth remembering:
To add title text in a new score, right click on the title frame -> 'add title/subtitle/composer'
(for arranger, use 'lyricist')To add copyright text, you can either manually add copyright info to the score properties tab (project properties in MU4), or use my copyright plugin (makes including the NSM URL much easier) which is linked with the templates below.
If you haven't created a new score, you might need to make sure that the mini-title on pages 2+ sets itself to the title itself, and not to "Title". To do this, go to File/Score Properties (MU3) or File/Project Properties (MU4) and enter the desired title in the 'workTitle' field.
If you're creating a sheet using the style file, you may have to remove the 'Pno.' abbreviation from the instrument. To do this, head to staff/part properties (MU3) by rightclicking on a note /staff part properties, or by clicking the settings icon in the instruments panel (MU4). From there you can delete it.
I've also created various MuseScore plugins to make working with the templates faster, they can be found in the 'NSM Tools' folder in the GitHub repo.
You can check out
my profile for other non-related (but definitely time-saving) plugins.