Before playing songs with chords, practice each part separately. First practice the melody of the song by itself (right hand part), then practice the chords by themselves (left hand part). Once you have learnt both parts, play them together.
Before you play, adjust the tempo to a comfortable speed. To do this, press the start button, and the drums will play by themselves. If the drums are too fast, slow the speed down by adjusting the tempo control. You can increase the tempo as you become more confident playing the song. If you are playing along with the recording, play only the right hand part. In this book, a chord symbol is only written above a bar when it is necessary for you to press a key or change chords. For example, in Exercise 13, just press the G key once at the start of bar 2, and let the keyboard play for two bars.