Screen Recording with QuickTime
Open the QuickTime Player app.
Choose File > New Screen Recording (control-command-N) to open Screenshot and display the tools.
You can click Options to control what you record—for example, you can set the location where you want to save your screen recording, or include the pointer or clicks in the screen recording.
More info here.
Click Record.
To stop recording, click the Stop Recording button in the menu bar
(it will appear at the top right of your screen, probably as the leftmost icon on the right side)
or type control-command-esc.