1. Scales
2. chord tones 1357 on all chords
   1. (the D7b9 at the end of the first line is an optional D Mixolydian)
3. Resolutions
4. Patterns 1-2-3 ,    3-5-3,     4-3-4-5,      5 3 1,    3-1-5,       1(high Do)-7-5-3
5. Make a soundtrap account or log in with a google account: https://www.soundtrap.com/
6. Here is the song on Soundtrap: Summertime on soundtrap .It won’t let you check it out without signing in.
7. Here is a different youtube version in case you don’t want to do soundtrap: Summertime on Youtube

For the melody, some scales and a play along track

check out this site:

https://www.jazzeveryone.com/jam-time/14-summertime-c-instruments/