Pretty much all tables work the same way as a calendar: days across, weeks down:
February
Sun Mon Tue Wed Thu Fri Sat
W1 01 02 03 04 05 06 07
W2 08 09 10 11 12 13 14
W3 15 16 17 18 19 20 21
W4 22 23 24 25 26 27 28
W5 29 30 31 01 02 03 04
Each day of the week is a column, each week is a row.
Columns run across from left to right, rows run down from the top.
So 24th February is the 4th row, 3rd column, and 3rd March is 5th row, 6th column.
Make sense?