Replace char on String

Hi All,

String strValue = "ABC TPT0694";

My String is as shown above, I am looking for a way to replace char at byte 6 (position 6) with another Char in String.

For example at location 6 it is "T" I want to replace it with char "O". can any one tell me how to do this

[293 byte] By [sameer_13va] at [2007-11-27 10:52:04]