okay so
step one: open blender
step two: delete the cube (this is 100% needed as the fabric of reality will collapse if you dont)
step three: add a cube
step four: give the cube a subdivision surface modifier
step five: go into edit mode with the cube selected (hit tab or hit the dropdown menu where it says object mode and find it there)
step six: f**k around with the verticies a bit
its not that hard we blender users promise