I only just started. Tried to jump high and kick coming down but was too far away. How do I get closer?

Extend hips.
Timing is important. Extend too early, you don't jump very high. Extend to late, you go too far away.

Always remember, press 'R' to view the replay again, press 'P' during that to pause, 'shift+p' to go by one frame, 'E' to start editing the replay again (moving joints etc).
While you editing your replay, you can also shift+space to go by one frame, rather than just pressing space all that time. If you utilise it right, you works will literally be 10 times more accurate.

Oh, I didn't know I could do that with replays! Thanks I shall try now