Hi there, Perhaps you can read the manual.. and post specific questions? But lemme help by starting to introducing program mode and combi mode
1) Program mode is like a single voice mode where you play only 1 voice.
2) Combi mode is like a multi voice mode where you can combine many voices into 1 patch and layer them accordingly. Combi also allows you to adjust the key zones so you can create keyboard splits and zones etc.