Log into the Shopify Portal.
In the left navigation pane, click Apps and select Create app on the top-right of the page.
Click Manage private apps at the bottom of the page.
Click Create new private app.
In the App details section, enter a name for the private app and a contact email address. Shopify uses this email address to contact the developer if there is an issue with the private app due to an API change.
In the Admin API section, provide the required permissions for the app to access the required areas of your store.
Generate API credentials.
Optional: To use the Storefront API, select Allow this app to access your storefront data using the Storefront API, and then select the types of data you want to expose to the app.
The Admin API section shows the app's API key and password.
You can use these credentials to make authenticated requests. Private apps can authenticate through basic HTTP authentication by using their Admin API key and password as a username and password.