Welcome to the SimpleTank bonsai forum. If you have questions about how to do something on the Microsoft bonsai web site related to this example, there are various support engineers that peruse this forum regularly.
If you came across this forum before accessing the sample, be sure to check the Azure Marketplace for the "Get it now" Simple Tank bonsai sample. It's free, and a fantastic starting point, if you want to learn about machine teaching with bonsai.