ust open your terminal and go into your directory (where the HTML file lies), and start the server using one of the commands below.

python -m CGIHTTPServer 8360
python -m http.server --cgi 8360
python3 -m http.server --cgi 8360
This will open the port for you.

Then direct your browser to http://localhost:8360/YOURFILENAME.html The default one would usually be index.html ;)