In this guide I'll help you how to read Underground Passage map. Basicly all you have to do is to read this spreadsheet and you might understand everything. If you have problems with, here is a video:

Spreadsheet: https://docs.google.com/spreadsheets/d/1_zm_YjohEajHwPW9cAlVPK2tlVYpYBGTr_HmCniE65E/edit?usp=sharing

Video:

I hope this will help you.