How to auto hide the dock
Here's how you can autohide the dock if you wish to do so.
1. Click on the Apple Menu on the top left of your screen.
2. Click on System Preferences.
3. When the system preferences box appears click on Dock.
4. There will be a box next "Automatically hide and show the dock". Click on the box to put in a check mark to allow the dock to autohide.
That's it. Drag your mouse pointer to the bottom of the screen and the dock will appear. Move your mouse back off the dock the dock will disappear again.