I am currently learning how to use Blender. I want to extrude this upper face along the three edges so that it extrudes into the tip of a pyramid, if that makes sense.
Hope you understand what I mean and can help me!
I don't think there's an extrusion, but there is an extension.. sliding those vertices along their edges, beyond the edges' original extents. That would be GG, either holding down Alt, or hitting C, to release the clamp.
The slide won't automatically stop at the point of the pyramid.. it can go beyond it .. that may not be what you want.