Where to start.... in AC8.1 in the AC Help menu there are three sections dealing with Trussmaker. On the AC8.1 installation CDs there are PDF files with the same manual.
There is a movie for Trussmaker that came with ArchiCAD 7 that showed how to use it as well as the built in Help manual.
Also there is a nice tip here...
http://www.graphisoft.com/support/archicad/archiguide/techtipsept2002.html
AC versions 3.41 to 25 (UKI Full 5005).
Using AC25 5005 UKI FULL
Mac OSX 10.15.7 (19G2021) Mac Pro-2013 32gbRam AMD FirePro D500 3072 MB graphics