help please

Ok, I have had a 2000xl for a couple of months now - Think have just about got to grips with the (very) basics - have been pouring over the manual but am surely missing something fundamental which would appreciate someone spelling out for me - and apologies if this sound thick to the seasoned users
One key question
If i sample say the first 4 bars in a song - I want to loop and have this as the basis of my song (which I can do) and then sample & further layer additional sequences over this? ( which I def can't!) Using song mode it seems to only allow playing one sequence after another? How do I play more than one sequence simultaneously and further ensure timings all fit.
....going mad here...help!!

Use different tracks man. The MPC allows you to use 64 tracks at a time. You can also play multiple sequences on top of each other.

Yeah fair enuff - if that's the ticket then guess what I was really after though is a bit of a step by step twats guide for doing just that!!
If this is the way forward and anyone can be ersed doing this it would genuinely be hugely appreciated!!