Post Method in SharePoint online Folder suing Postman

I am trying to use Get and Post method in share Point Online from Postman . I performed all below steps till 4th step.

1. Register Add-In – SharePoint online
2. Grant Permission Add-In – SharePoint online
3. Retrieve the Tenant ID in Postman tool
4. Generate access token 

Once completing all steps when I am trying to use URL to get and Post it is showing Invalid Host Name and Error 400