Open the terminal with ctrl+alt+t, by clicking it from the taskbar, or by navigating through the menu (Raspberry Pi icon -> Accessories -> Terminal). In the terminal, enter:

sudo apt install code

sudo apt install code

The output should look something like this. A good way to make sure that something has been installed is to check the line that I circled below.

When you open it, it should look something like this, but as long as it opens and you don't get any error messages, you're probably fine.

If you'd like to install the CircuitPython extension, click the extensions tab (circled in red below), type CircuitPython into the search bar, and install CircuitPython v2 by wmerkens.

Now you should be ready to use VS Code on your Raspberry Pi. For more information about using VS Code, click on the link labeled "VS Code Documentation" on the sidebar.