Michael Raz has written a set of utilities and guides centred around MapRun events at https://maprun.raz-family.ca/ that includes a detailed guide to working with oomap in conjunction with OpenOrienteeringMapper and Purple Pen.
YouTube has some videos based on https://oomap.co.uk but still very relevant for this version.
Firstly, Ollie O’Brien’s comprehensive walk-through (70 mins):
Secondly, a short summary (4 min) of the major functionality from Southampton Orienteering Club: