Hi guys, I want to modify that myArr() value?

here is myArr()

myArr(0,0) = "john"
myArr(1,0) = "Jan"
myArr(0,1) = "mary
myArr(1,1) = "Dec"
myArr(0,2) = "sam"
myArr(1,2) = "Feb"


I want to modify "mary" , "Dec" to -> "mary" , "OCT"

how to start ?
please!