Connecting GitHub to Jenkins running on docker toolbox
Your configuration is wrong. Here you add http://192.168.99.100:8080/ is a local Jenkins URL. Github does not connect with the local URL. Also you give the wrong webhook-URL.

Please add your public IP of Jenkins in your webhook like http://35.24.128.75:8080/" And GitHub webhook payload url is like http://35.24.128.75:8080/github-webhook"

for Full webhook configuration please watch this video: https://www.youtube.com/watch?v=wsnq9uGAWkM&amp;t=460s