Testing your SharePoint Framework development environment
To test that everything works, we are going to create a HelloWorldweb part.
Step 1 - Creating a folder for the web part
First, start Command Prompt or PowerShell. A quick way to do this anywhere in Windows is to press the Windows key with R (Run), and type cmd in the Run prompt. An alternative way is to navigate to your project folder in Windows File Explorer and to right-click within the folder while pressing the Shift key and selecting Open Command Prompt here.
Type the following commands to create a folder called helloworld-webpart and then navigate the Command Prompt to that folder:
md helloworld-webpart cd helloworld-webpart

Step 2 - Running the Yeoman SharePoint generator
Next, type in the following command to start the Yeoman SharePoint generator:
yo @microsoft/sharepoint 
Click Enter to accept the solution name to be helloworld-webpart (based on the folder we are in), and again to accept the current folder to hold the...