You want to build songs with your melodie, your rhythms and your tones
The most basic is whole notes. you can also do quarter notes, eighth notes, and syncopated patterns.
Every great song has variety in it.
Eighth notes are great for energy. theres no syncopation involved. They will go over pretty much any vocal , drum or guitar rhythm.
Take your top 2 notes and bottom note (separate hands) and alternate them for something different.
Luke demonstrates some examples.
Another great way to create rhythms is arpeggios. they can take the foundation of the song.
Syncopated rhythm = simple melody, syncopated melody = more simple rhythm.
Its really important to play with a metronome, and practice a lot!