Understanding and Solving the Rubik's Cube Without Algorithms
6.a. Making the cross
The first step is very simple and consists of forming a cross on one of the faces, but making the sides coincide with the centers of the adjacent faces, as illustrated below.
In this example at Figure 6.1 the cross was made on the white face (facing upwards), note that the colors of the sides must match the centers of the side faces.
You are now able to do this easily, using “go, swap and back” moves or even simpler ones.
App source: animcubejs.cubing.net/animcubejs.html