Using the root triads - the triangles shown in these diagrams - is a starting point, but rather limited. Two variations to consider, right from the start in my view, are:
1. Spread chords. Starting with the triad (triangle) as shown, take out the middle note and instead play it an octave higher (on the other side). Can often sound mellower than the basic triad.
2. First inversion. Starting with the triad as shown take out the bottom note and play it an octave higher (on the other side).
These two techniques, along with the root triad, will allow you to play a more satisfying accompaniment where the top note of the chord (or the bottom note or even both) follow a musical progression.
REALLY HELPFUL TIPS! Thanks from Mary-Louise