Don’t make any changes that aren’t asked for by the instructions. You deleted the existing h1 element with the text CatPhotoApp but the instructions did not ask you to do that. Any unexpected changes will most likely cause you to fail the tests. I would reset this step to get the original HTML back.
As for the instructions in this step, you are asked to do one thing:
Below the h1 element, add an h2 element with this text:
Cat Photos
Once you have reset the step to get the h1 element back then you want to add an h2 element, not an h3 element, and the text inside that element should be Cat Photos. So once you are done you should have both an h1 and h2 element in your HTML.