Instructions
Click a unit or building that you want to set to a hotkey. Press and hold "Ctrl" and press a number on your keyboard. That number is now bound to the selected unit or building. A tab will appear near the bottom of your screen, with the number you chose as your hotkey.
Press the hotkey twice to instantly center the camera on the chosen unit or building. For example, if you bind the 1 key to your nexus, press 1 twice to center on your nexus.
Press the hotkey once to select the desired unit or building. For example, if you bind the 2 key to a worker, press 2 once to select the unit. Selecting the unit will not center the camera on that unit.
Use the preset hotkeys to choose an action for a building or unit. All units and buildings have at multiple actions governed by preset hotkeys. For example, when you click on a Zerg hatchery and press S, followed by D, you begin creating a drone by default. You can change these hotkeys by opening "Menu" and clicking "Hotkeys."