Open web preview pane when running python script

I would like to customize what happens when I run my python program. How do I make it so that it opens a preview pane to a specific URL? Do I need to make a plugin or extension for that? Or is this done using launch.json?

Note: I’m not very familiar with VSCode (I come from the world of Vim).

Should you program be responsible to trigger the preview when some conditions are reached?

@akosyakov I would like for it the preview to open as soon as the Python script is run in the terminal.

What I’m doing is creating an integration for building GUI applications by starting an Xorg/VNC server and using an HTML5 VNC viewer in the preview pane (I’m building this for a beginner Python class that uses Pygame).