Okay so you have the four main chords of G: G5, C2, Em7, and Dsus.
Experiment with different orders of chords. These are called progressions.
A couple examples of very common progressions to learn really well:
- G5, Dsus, Em7, C2
- Em7, C2, G5, Dsus
- Try more. Play around with them.
And now you can play most songs in G in the open chord form. Have fun.