Finally, play a C major scale with both hands. Do not rush! Play it slowly and nicely. Listen to your playing so that you can hear what a major scale sounds like. Practice it until you can play both hands without the score.
How does the tonic work in music?
The first note of a scale is called the tonic. The seven pitches in a major scale have hierarchical relationships. In other words, some pitches are more important for defining the key. The tonic is one such note. The tonic center comes at important places of the music to confirm the key to the listener. For example, a piece in C major may end on C to confirm this is written in the key of C major.
For further practice, play the C major scale in two octaves. Follow the fingerings.