Hello all, I'm brand new to this forum so please bear with me. My background in programming is not strong, VBA is the only language I have any experience in and it's minimal at best. I usually utilize excel in the worksheet formula manner but have just recently started expanding into simple VBA programs. I find myself severely lacking in technical language and (obviously) familiarity. I purchased a book and it has helped some but i'm not getting the wealth of language examples I feel that I need. What I'm looking for in this post is help figuring out how to write it, not just completed written programs yet. Thank you in advance for any help you can give.

Abstract:
Part of my work is tracking/analyzing results from water samples of 2 systems, 3 tests each. Current program has userform for entering data and populating entries chronologically into a spreadsheet. One of my duties requires reporting Fiscal year quarterly averages of these results. I have created a user form that will take input fiscal years, and allow me to check boxes (4 per year input, one for each quarter) which will eventually determine how many times this code segment is used, for which date ranges it will be used for, and for which cells will be populated in the reporting worksheet.

Requirements:
This code will run when a checkbox=True. It will cycle down a column of dates, checking each cell against a conditional date range. For those dates that satisfy the first condition it will advance and check against a second condition. If the second condition is satisfied it should advance a counter variable by 1, and increase two different variables by the sum of the indicated adjacent row cells. Once this is complete is should advance to the next row and repeat process until second condition=False. At this point it should output the value of both variables divided by i respectively to another worksheet cell location. See flowchart for further clarification:

VBA_Project_Flow_Chart.jpg
date conditions shown are examples, actual conditions will be declared for each checkbox prior to code

Where would you start? What type of Function/Loop/etc would you use? How would you ensure it only cycled through your "Date" column while looking for True/False conditions? Once again, thank you for your help.