To send MIDI signal out of Sensory Percussion, you'll want to choose a MIDI hardware output. Once you do, you'll be prompted to name the output and choose the MIDI output channel you want to send it to. Both of these can be changed later.
MIDI hardware outputs allow you to send different types of MIDI messages out of Sensory Percussion and into other programs that accept MIDI. The possibilities are pretty endless with MIDI; use it to control visuals from the drums, play back music you've created in other software, or control a host of other MIDI-mappable parameters across a variety of different programs from behind your drum set!