Probably from reading the Trainz manuel (sie senior).
Or by asking some people on the forum.
I have almost figured out just about, what all the buttons do, and how to measure in metric (as Trainz heights are), and convert them to Imperial measurements ... PM me and I will be glad to assist ... although I don't have TS12, and in TS10 I have no experience ... but I presume all versions are basicly the same surveyor wise.
TS10 and TS12 have layers, and the top 2 layers are what you build and save on ... I am told