The easiest way to put together the white cross is by a two-part procedure:

Part one:

At first we form a white cross around the yellow cube (top image, in the middle), as shown in the photo. For now, we will not be interested in other colours.

Spotting the starting positions of the white cubes and goal one: white cross around yellow

The next video will show you the moves (rotations) to be used to reach goal one.
Pay A T T E N T I O N to the prearrangement rotations before putting the cubes to their final position.

Part two:

Now we are paying A T T E N T I O N to the colour cubes on the sides of the white cross and the colours in the middle of each side of the Rubik’s cube. When we match these two colours, we rotate their sides for 180 degrees.

Matching colours and 180 degrees rotation sides of Rubik's cube - final goal: white cross in first layer