Applying the R.O.T using Photoshop

I applied the rule of thirds to this image of me using photoshop.

First, I clicked Ctrl + K, then guidelines and grids. Then I changed the 1 to 100. Next, I changed inches to percent. I made sure the subdivisions were at 3 instead of 4 and changed the color to light red. I clicked "okay" then the crop button. Lastly I clicked the window button, clicked the snipping tool, and took a screen shot of the picture with the rule of thirds.