The "Cyclemaker" window is composed of 2 complementary commands called "Cycle Step" and "Cycle Side", features dedicated to cycled animations such as walks or runs.
By working with both ones, the 1st command allowing to generate the 2nd half-step, then the 2nd command allowing to rework a side on the complete cycle and past it on the other side, you can produce fast & well a lot of animation cycles!
: Generate the second half step keyframes based on the first half step ones. Meaning Cycle Stepit duplicates all your keyframes, mirror them and put them at the end of your animation.
: Mirror the selected controllers to the other side, time shifted from one half step. This is generally useful when you want to replicate the changes you made on one side of your cycle onto the other side. Cycle Side