Create an Azure AD B2C Directory
Note the Domain name, it'll be used as the tenantName.
Register your application Follow the instructions to create an application and enable both Web App and Native client. Refer Register a web application and Register a mobile/native application
Enter the Reply URL as http://localhost:8100 or any port from wher you'll be serving your app.
In Application Claims, select Email Addresses too.
Note the Application ID . It'll be used as the clientId.
Create a sign-up or sign-in policy
Note the name of the policy. It'll be used as policy.
Create a password reset policy
Note the name of the policy. It'll be used as the password-reset-policy