Here's the real way to do it (without details):
- Demux and remove the audio/subtitles from the MKV container with MKVExtract GUI and MKVToolNix
- Convert audio stream to AC3 or MP2 using BeSweet (or with BeLight...which really is BeSweet with a GUI)
- Make an Avisynth script to load up the original MKV
- Use a MPEG2 encoder, like TMPGEnc, to encode your Avisynth script (which really is your MKV video stream) to an MPEG2 video stream (.m2v file)
- Use a DVD authoring program (like TMPGEnc DVD Author) to encode your DVD
- Burn your DVD
If you need further explanation on these steps, use Google or ask SPECIFICALLY what you don't understand.