Add some requirement into Android app

I have https://codecanyon.net/item/event-app-with-material-design/22496822 this application and want to need some implementations

1. Check user registration duplicate entry & showing error if exist
2. Restrict user to book ticket if user enter exist email, name and phone number
3. Add blog where admin can post the content from admin side (backend with php) and blog content reflect
into the user app screen