This lesson will provide 8 exercises to help you learn how to tap a backbeat while you play a melody simultaneously. The two most common types of rhythmic backbeat percussive accompaniment are taps and slaps. Taps and slaps differ from one another. A tap is when you pick a note and use your thumb to tap on the ukulele’s body (above the strings) at the same time. A slap is when you use the palm of your hand or thumb to slap above or directly onto the strings. A slap is performed without playing a note simultaneously. I would recommend you master slapping before you attempt tapping.
Here is the lesson on Slapping: https://rockclass101.com/add-a-backbeat-to-your-rhythm-playing/