Create Custom entities in MS Dynamics CRM 2015 online

1. On the  navigation pane of CRM, click on the Settings --> Customizations --> Customize the system(Also can proceed from custom solution)
2. Click the Entities node in the solution explorer and then click New in the menu bar.

3. Complete all required fields Display Name, Plural Name and Name.

    

4. Select whether the entity will be owned by a user or team/organization

5. Select Areas that display this entity section, select Sales and Marketing.

6. Click Save and Close to close the new entity form.

7. Publish the customization. Entity will be seen under Sales and Marketing.