First you will want to grab yourself a copy of the latest1 factorio server.
Once you have it unpacked you need to generate a new map or upload an existing one.
./bin/x64/factorio --create <mapname>
After that all you need to do is start the pm2 daemon.
pm2 start ./bin/x64/factorio -- --autosave-interval 15 --start-server <mapname>.zip
Have fun building awesome factories!