Once you set up all the required installation to start the development activities,
You will see the folder structure in your folder. Here in my case, I have ran it on administrator folder in the C drive.
Now you need to run this web part template created by yeoman, Technically you need to package it and push to SharePoint ,
Gulp is the main component and it will packaged with all certificates to run on the browser.
Type the below command in PowerShell command
gulp trust-dev-cert
It will install the certificate on your local machine, trust it when prompting on windows alert box.
gulp development certificate installation
Now you are ready to run the SharePoint Client WebPart into SharePoint Workbench.
To do this,
type the command : gulp serve
It will start the browser with localhost server