Create a tab Notification Centre with messages list inside it in customer record

Solution

First create a subtab Notification Center in the customer record

• Navigate customization->Forms->subtab  

  Entity->Notification Centre

 Then created a custom record for notification with a field message,message subject and date and set its parent as the customer.

• Navigate customization->list,record and field ->Record Type

Notification

Navigate to the notification tab in the customer record where we can add new messages by clicking the new notification  button.