To map MIDI outputs from your Theremini, first connect it to your computer using a mini USB cable. Depending on your DAW, you may have to set it up as a MIDI device. Once you have done this, the Theremini should automatically send MIDI data from each of its antennae.
By default, the Theremini will send MIDI CC 2 from the volume antenna and CC 20 from the pitch antenna. However you can change these to any MIDI CC by pressing the SETUP button on the Theremini and then navigating to the MIDI CV Setup window. From there, you can adjust the CC for each antenna as well as change the resolution from 7 bit to 14 bit if you choose to.
Your DAW should automatically receive MIDI CC information whenever your hands come into the field of one of the antennae. Then use the mapping function within your DAW to map these to whatever parameter you wish. For how to do this, consult the manual for your specific DAW.
Keep in mind the Theremini does not send Notes, only MIDI CC’s.