First, get the wad here: https://www.doomworld.com/forum/topic/134292-myhousewad/

Second, download GZDoom here: https://zdoom.org/downloads

Third, have an original copy of the doom2.wad file.

Grab both doom2.wad and myhouse.wad files and drop them onto gzdoom.exe. There was also some nice GUI frontends that help you out like ZDL or SSGL, but this is the most direct.