Magic DeckMate is designed to maximize screen space and fit into your play area as seamlesssly as possible. It will orient to portrait or landscape depending on how you orient your device. Much of the functionality is accessible through the menu. You can find the menu button just below your life counter. This button will change depending on which color scheme you choose.
When you start up the app for the first time, the tutorial will guide you through the controls. If you wish to see the tutorial again, you can find it in the menu: