Update column based on a cell on another sheet

I'll do my best to describe my problem and what I want to achieve. As it stands, I have two sheets. One called "First Sheet" and another called "Secondary Sheet". On Secondary Sheet, I've used importrange to obtain responses from a Google Form.

I would now like to see if a username from First Sheet, Column A, can be found in the Secondary Sheet, Column B. If it can be found, I would like to update the cell to the right.

For example, if the username at A5 on the First Sheet is found on Column B in the Secondary Sheet, update D5.

This should be written to the cell permanently so I'm looking to use a Google Apps Script only. I hope my explanation was clear.