How to insert a character when editing a file using ISPF Edit via TN3270?

The editor in mvs3.8 TK4- is very different from the editors that I have used in Windows and Linux. I am trying to figure out how to insert a character between two characters in the editor. For example:

//HERC01C JOB (COBOL),

If i want to insert an O after C to //HERC01CO JOB (COBOL), the only ways i can do are by backspacing from the end of the line upto C and type everything after that again; or by moving all the characters to a position to the right using )1 command and the typing over everything form the beginning till C. Is there a way to add O here after C so that it will insert O and automatically move all the characters after that one place to the right?

Solution

I am presuming you are using the ISPF editor

enter nulls on in the command line. This will convert trailing spaces to nulls
if the line is full, you will need to split it
position cursor where you want to enter the new character
Make sure you are in insert mode the insert key swaps between insert and over-write modes.
Type the character.