How to Automatically Move Text to next Form Field

I am creating a fom that has 36 text boxes (they are actual boxes)...Where you add, for example, your name [L] [A] [U] [R] [A]

How can I make the field automatically move to the next text box once I insert a letter (or number)?

Is there a particular script?  I found one, but it was for Javascript and I couldn't understand how to insert it into the Custom Format Script.