To do this I select the debug button on the left vertical column

(bug with a play button)

and put a break point in the first line of code

(click to the left of a line of code to put a red dot there)

then press play.

A drop down menu with lots of stuff I don't understand drops down and I chose the python file option. This is telling the debugger to interact with the code as if it's written in python language. The image below shows you what you should see if the debugger is configured correctly. Note: there's lots more behind configuring the debugger in vscode. The debugger is really one of vscode's most charming features and is super powerful.