HOW TO BUILD.txt

1) Open command line

2) Type this...
ubuntu
...and press the Enter or Return key.

3) You are now using the WSL, which allows Windows to run linux commands. Type the following...

cd /mnt/i/OpenTTD\DevProjects\GitHub\Gadg8eer\OpenGFX-Mars-reMOD-Late-Start\ogfx-mars-ext-rv
make NML=/home/kidpunk/.local/bin/nmlc

4) If that doesn't work, you don't have WSL installed. Contact someone in the OpenTTD community to get help installing WSL and the required libraries (Python, GCC, NML). Then try step 3 again.