Build the project once the terminal as follows, assuming you've already installed node.js and yarn, This will downloading all the project's node.js dependencies. You need to do this only once.
yarn
To work with this sample VS Code extension, just launch VS Code and feed it this directory
code .
The VS Code project is set up to dynamically build the code (using npm watch). So, as you change code, simply look in the PROBLEMS view to ensure everything is good. To run or debug the extension, use F5 or CTRL-F5, respectively. This will launch another instance of VS Code that has the extsension loaded. Hit CTRL-SHIFT-P to bring up the command palette, then select Hello World