>Your codes work fine but I want to know about
>*4+1
>
>Please help to understand

Position of the month name is calculated as (MonthNumber-1)*4+1, where
(MonthNumber-1) - number of month before current
*4 - # of charcters for each month name (3+space)
+1 - convert offset (which start in 0) to position (which starts with 1)