Hey,
First, check the tuts by AcidBubbles where he explains how to use it and adjust the keyframes.
Stop all animations, then go to the specific animation you want to modify. Select the control nodes (i.e. probably hand/elbow/arm), then click the keyframe you want to adjust (the small black squares along the timeline). Now if you go to the person atom and move the control node that's selected on the timeline, it's going to replace that position in space to the new one you moved to. You'll have to do this for all keyframes of that control node in a given animation.
If you provide a screenshot of the animation you want to adjust might make it easier to help you out.