After the Lock Screen you will now be at the Home Screen. The Android Home Screen is your "desktop" in PC terms. You can place shortcuts to your apps, useful widgets, and folders.
You can add more home screens as you want, by default, it has 3 home screens which you can access by swiping to left or right of the screen. More screens, more space.
On top of the home screen is the notification bar, where you can see the time and other notifications. You can drag the bar down to expand it and you will see controls for the WiFi, Bluetooth, Ringer, and Screen-rotation.