How do you decode the message? And how would you create your own message?

spacel a b d e flg h i 0 123 45 67 819 n 14 0 15 P 9 16 17 r 18 S 19 t 20 u V 21 22 w 23 24 y 25 z 26 10 11 12 13 Suppose we used the same encoding matrix A = 2 -1 0 0 1 1 -2 0 3 1 -20 1 1 1 4 as above to encrypt a special message: VXMSPFDVATYMLZQSXXCRMCPGVJAYVIXSHFWQDITWQME WYKJHBRILJGDRJAY