Don't worry too much...
You get the better sequencer in the MIDIs history, in my opinion, but need some help  to learn about. My first mc50 come in 1991.
I'll explain some topics to help you.
1- don't power up the mc50 with a disk in
   the drive (to prevent some unmissing
   configuration)
2- it have 2 MIDI out, the port 2 have a 
   Thru option on default configuration. Use 
   the port 1 to send to master keyboard and 
   the port 2 to send to other devices and 
   modules.
3- also have the rhythm track, to record in 
   that, set the option REAL to RHYTHM and 
   press the rec button. Then select first 
   pattern, press sometimes the enter to 
   select a display with ............ in the 
   down line.
   Press shift+play and record the pattern   
   loop(make sure to set the channel 10 in 
   the master).
   After this, press stop, press rec and 
   select the r-track, press enter, and 
   select the pattern that you record 
   (ex:1), everytime the bias option in zero 
   (0).
   Repeat this procedure to record other 
   patterns and assembly your rhythm track.
I hope help you.
Any doubt contact me at
bortolato1@yahoo.com
Greatins from Brazil.