Adding an Application
After Logging into your account, select the Add Application Button near the middle on the right.
Enter an Application Name, then click Create Application to continue
In this view, you will want to securely store the generated Application Key, Client Id, and Client Secret. You will need these when authenticating the application. Click Select Scopes to select the scopes needed when accessing the API
For the different scopes, show you can click the arrow on the right to show scopes related to that category.
Hovering over the "i" next to the scope will give more details about what the scope gives access to and what fields it uses.
When selecting a scope, you can choose to have no access (scope not selected), read only (scope name), or write (scope name.write). When running through the authentication process, you will need to include the scopes required for the application. Save changes when all scopes have been configured.
Only select the scopes needed for your application. You should never give an application more scopes than it will use.
Most of the time, you will want your application to be able to refresh the authorization tokens. Be sure to select the Miscellaneous > offline_access scope.
When you come back into the application, viewing it will show the newly selected scopes at the bottom.
Select App details near the top right to add a Redirect URL. This URL will manage the authentication code and sending the request back to the server to obtain the authentication tokens and refresh tokens if specified.