How to create a multiple activity in java

Question

I want to create an app using AIDE, which randomly generates a number and tell if it's even or odd in the background. That is, the main activity xml file shows a layout telling the user to guess by clicking an even button or odd button below. When a button is clicked, it will create another view which tells whether the guess is right or wrong, with a button below with text="Go Back". So it's at this point I get stuck. The "Go Back" button does not click, I wanted it to go back to the previous view again.