You’re trying to make a “walk cycle”.
Could you be more specific regarding the problem?
1. do you have the 6 frames, but don’t know how to loop them?
To solve that, render them as a 6-frame movie, then import and interpret the footage so it loops. Look in the Help under “interpretation”. If you don’t want to render it now, precompose the animation, apply Time remapping, then use a loop (“cycle”) expression to loop the precomp.
2. do you have the baby as a series of mage layers, one for each limb/body part, but don’t know how to animate them?
Search the COW for “IK” and “ebberts”. This isn’t easy, but it can be done with a bit of patience.
3. if those don’t solve the problem, let us know exactly what you have, and what you need to do.