Weirdly, this Personalize screen has no real home. It appears in PC Settings only when you haven’t tapped any of the main headings (“PC and devices,” “Accounts,” and so on). It is, in effect, the home screen of PC Settings.
In any case, Personalize offers three very visual controls. Each is actually just a link to other categories in PC Settings, as follows:
Lock screen. Here’s where you choose a photo as your Lock screen backdrop and control which apps are allowed to run in the background so they can display information on the Lock screen itself. (It’s a shortcut for the “PC & devices” category of PC Settings.)
Account picture. What image do you want to represent you on the Login screen, and at the upper-right corner of the Start screen? That’s the question you’re asked here. Use the Browse button to choose an existing picture of yourself from your Pictures folder, or use the Camera button to take a picture of yourself right now, using the built-in Camera app. (It’s a shortcut to the Accounts category of PC Settings.)
Picture password. As noted on Creating a Picture Password, you can install a photo to touch or trace instead of typing in a password to unlock your PC. This shortcut to the Accounts panel lets you set up or change your picture-password picture.