Today I worked on lesson 6, which deals with Saving your Progress.
I had this image and I was saving just this layer (as you can note that there are numerous layers for this specific photo)
I went up to the file menu and picked Save as and this popped up. I changed the name to Prepress cover and changed format from Photoshop to TIFF. Then turned off layers and turned on As a Copy and hit save. Then I had to change the image compression from None to LZW.