The press h to hide all those vertices, and you are left with just the eye socket vertices visible in the window, to make it easier to move the verts around. When you’re done, Alt+h will unhide the hidden mesh.
When you’ve finished this tutorial, would you mind taking a look at Modeling a Head using Face Loops ? It’s a work in progress, so there isn’t a lot of explanation right now, but I would appreciate feedback, especially from newer BlenderArtists, on what needs explaining.