The following tutorials apply to current Fritinzg versions (many of the others are for older versions.)
I lately learned there aren’t links to the videos in Old_Grey’s tutorial so you need to do a google search for the title and then they come up on YouTube.
It is complex and not likely to get that much easier, however I believe the developers are working on an update to parts editor (which was not finished when development stopped in 2016, it restarted again arourd 2019.)