Move 1. Move R2 over to left, below L4.

Move 2. Move L2 over to right, below R4.

Move 3. Move R3 over to bottom left, below the red thread.

Move 4. Move L2 over to bottom right, below the red thread.

Your yarns should now be in this order:
R1, L1 and R2, L2 are black, then R3, L3 are red and R4, L4 are blue.

Move 5.  Move R1 under the new R2, over R3 and R4, and place below L4.

Move 6. Move L1 under the new L2, over the other threads on the left, and place below R4.

Tension the braid by holding the threads, and pulling your hands gently apart.

Repeat moves 1 to 6