You have not indicated how you are currently structured. Ideally, you would have a Companies table containing Company name, address etc.
"I have not discovered how to go and auto populated related fields to the company that I am working with"
... then I assume you have ANOTHER not-yet-identified table where you select the Company name from a drop-down and you want the Company data to auto-fill in this other table? Is it something like Invoices where you must plant the address as static data?
You may want to read this tutorial. It spells out two approaches that work. The results from each are quite different so you have to evaluate the needs and function of your database to decide which option is the best one for your project: Auto Fill