Get your Google Server API key and project number.
https://documentation.onesignal.com/docs/generate-a-google-server-api-key

How to Change One Signal App Id in Android Studio

• Open Android Studio > App > com > example > brandpeak > MyApplication.java
• Enter your Onesignal App id inside "onesignal_app_id"
  private static final String ONESIGNAL_APP_ID = "onesignal_app_id";

How to Change One Signal App Id in Admin Panel

How to Send Notification From Admin?

• Open Admin Panel > Notification
• Enter title and message which are mandatory
• Upload Image if you want to show in notificaiton. This is optional

• If you want to open a particular category, select the type category then select any category.
• If you want to open a particular festival, select type festival then selects any Festival.
• If you want to open the URL in the browser select the external link then enter the URL.