I Cannot Put Last Piece In
I have watched Every video every guide and cannot get the last piece in
for the new rubix cube
As you probably have seen in the videos and the guides, standard procedure is to build up the cube until only one edge piece (which has two faces) is left. Then turn the top layer 45 degrees and push in the remaining piece. This requires some force, especially in new cubes.
However … You will need all the play that is available in the cube which is why this is best done holding the cube in your hand, not on a hard surface. Allow as many pieces as possible to give way a bit.
Alternatively: Each of the six (one face) centerpieces has a screw inside. You may be able to remove one of the six covers and unscrew the piece.