1. According to the encyclopedia query, open lightroomclassic program on Mac computer.

2. After entering the lightroomclassic interface, click lightroomclassic at the top of the screen and select the "Edit Watermark" option.

3. On the right side of the pop-up window, click "Text" behind the watermark style.

4. Then, enter the watermark text below. Finally, continue to edit the style and effect of the watermark.