To start a screen recording on a Mac, you will need to use the built-in QuickTime player. Here are the steps to follow:

Open QuickTime player on your Mac. You can find it in the Applications folder or by searching for it in Spotlight.

Click on “File” in the menu bar at the top of the screen, and then select “New Screen Recording”

A small window will appear with recording options. You can choose to record the entire screen or just a selected portion. You can also choose whether to record the audio from your Mac or not.

Once you have made your selections, click on the red button to start recording.

To stop the recording, simply click on the stop button in the menu bar, or press command + control + esc.

The recording will be saved to your Mac’s hard drive and you can find it in the Movies folder.

You can also start a screen recording using keyboard shortcuts by press Command + Shift + 5, And then you can find the recording controls on the screen. To stop the recording press the same shortcut.