vba Find a last row, loop down, enter data to cell, check for errors

hi guys need urgent help pls

I need to find last row in my sheet and and enter the number into the indicated cell, i found how to do with MsgBox, but teacher doesnt want meassage box just a last row number in that cell
And I have to do with VBA

then I have to loop down the number of students and enter the total into indicated cell ( total number of students) again with vba. also there is 1 or 2 blank rows, so I have to avoid counting them

I have to calculate percentage in 2 coloums, i.e colomn a is 5, colomn b 10, i have to loop down and calculate 5/10*100. some rows has "abs" there so I have to edit the code to check for "abs" and avoid it and pick only numbers
also I have to check the result wit another colum f
I normally use iferror(colomuna/columb,abs)
but she wants VBA
pls help

last I have to debug following sub to display each students name

I thank you all

Sub students_error()
    Dim row As Integer
    Do While ActiveSheet.Cells(row, 2).Value <> ""
    If ActiveSheet.Cells(row, 2).Value <> "" Then
        MsgBox ("Student name #" & row & " is " & ActiveSheet.Cells(row, 2).Value)
        Dim row As Single
        row = row + 1
    Loop
    End If
End Sub