I’ve uploaded a video to YouTube showing you one of the most important chord relationships in music. It’s known as I IV V (1 4 5) and can be used in any key when you learn how these relationships appear on the fretboard.
This is a great place to start when learning about using the diatonic chord scale in your songwriting. It should be see as an essential foundation element which you’ll later build on.
You can learn more about songwriting on guitar here.