I couldn't tell you how much to add because it depends on your soil. You could test it by mixing your soil with whatever amendment you choose in a nursery pot in different proportions to get drainage you are satisfied with.
Here are some videos
https://www.youtube.com/watch?v=waQADcf2mY8
https://www.youtube.com/watch?v=QS7qQVOzK7g
https://www.youtube.com/watch?v=0feB5WwUgMQ
Adding organic matter every year is the best way to accomplish this