General MPC help...

How do you get a 2nd instrument after you go to track2, track perams, track type MIDI & MIDI channel one ? Say I already have Brass instrument and I want to go to another track to add a piano melody. How do you do this without changing the 1st instrument, I wanna keep the Brass plus piano ?

That depends on what you are calling the "2nd instrument". If it is a program in MPC's memory that you have loaded along with the brass program, just use the jog wheel in track parameters screen to go to a track program selection screen and choose the piano program you want to play on that track. If it is a sound module or a synth, that you want to play back a part recorded on a particular track in MPC's sequencer, then you have to assign a different (from the brass instrument or program) Midi channel to that track in track params screen, then set up your synth or sound module to receive midi data on the same Midi channel. If you want to play both instruments from one sound module, then make sure it's multi-timbral (i.e. is able to play different patches simultaneously and could be configured to receive midi data on different channels to do that).