Please do it on VBA code excel, show me please

In VBA, write a subroutine to calculate the sum of two 3 times 3 matrices. A user should be able to input matrices and your program should perform the calculation and print the result on the spreadsheet. Comment each line of your code and put it in a text box on your spreadsheet. Demonstration your subroutine works property by computing the sum of [1 4 7 2 5 8 3 6 9] + [21 8 -3 4 5 16 6 0 42]