Use this message:
(FOLLOW THE “WHAT” example above)
“UCUMBERLAND IS A+”
Fill the message in the 4X4 MATRIX
and NOW Multiply by the AES MIX ROW – IN GALOIS FIELD (Below)
2311
1231
1123
3112
Remember the 2 is actually is actually 0010 
3 is 0011
1 is 0001
YOU ARE PERFORMING MATRIX MULTIPLICATION (DOT PRODUCT) AND REDUCE IF NEEDED. THE RESULT HAS TO FIT IN ONE BYTE