How do I fill out my W-4 so that I owe less tax at the end of the year, or possibly get a refund.

First, you fill out your name and address at the top, and then you go to part C.
Under single, if click single, you’ll have the most tax withheld for federal tax purposes, you’ll have the most money paid in towards the end of the year.
It’s a better chance for a refund or a smaller amount due.
Checking married filing jointly will have less federal tax paid in towards your liability.
For now I suggest skipping step two, three, and four, as they will only possibly decrease the amount of federal tax withheld.
If you have further of questions about that, contact your accountant.