Auto Advance Entry Field Focus in Perspective

Thank you very much for your response!
Unfortunately, I am not quite sure how to use the information provided in this link to find the answer. In order to advance focus, do I need to create a custom method for each numeric field? and then call them from somewhere else? Where should I use the focus command?

This is my first application with perspective so I am not quite sure to use which method exactly. I could not find anything for perspective and I found this link for vision: