Is it a prime number? #android

Hello guys i am a complete noobie to android and learning it.

i was given a task to make an app which produces a random number and then makes us choose whether it is a prime number or not pressing true or false buttons and giving responses in toasts whether the selection made is correct or incorrect.

please give me general guideline on how to make the app

and how to generate the random number and make it show up in between the string (Location marked).

Basically what i want

The arrow shows where i want my random number to show up