Use Loop in Excel VBA to calculate accrual sum of revenue

Hello all,

I have no experience in Excel VBA before, that's why I tried hard to use a mixture of Excel existing formulas to calculate the accrual sum of revenue for a school's course (with a duration of less than 12 months, and 6 batches of students), and I failed several times to do so

I've heard that we can use Loop in Excel VBA to execute the task easier and more efficiently. I kept searching but my limited knowledge of coding prevented me from success.

Would you please have a look at the attached example, and teach me how to generate a Macro to implement the task. Thanks a lot for your help.