1. First, open the PS software of the computer and take photos with grid lines as a demonstration.

2. Then select the edit option on the menu bar and click Enter.

3. Select preferences in the edit drop-down box, and then select guides, grids and slices in the submenu. Then click enter.

4. You can see the setting area of the grid in the open window. You can change its unit, size, color, etc. On the corresponding options.

5. Enter different units and different numbers. After setting it up. Click OK to change its size.

5. Finally, the effect style of changing the size.