Is it the XE-A206 cash register?If so, the instructions for programming the department keys are on page 32 of the instruction manual:
If you need to set up another department you will need to go through the same process as for the first 13 departments.
Ok, I understand now. I can't really simplify the process - it is quite complicated and you need to follow each step exactly.
If you aren't sure of any of the steps, or can't find some of the buttons, let me know and I can try to explain further.
Otherwise, you may be better getting your local Sharp dealer to complete the programming for you - some could almost do this programming with their eyes closed.
Let me know your zip code if you need contact details for your local dealer.