You can find Zed's tutorial in the pivot tutorial section and Mitch's in TheDarkDemon.com
Is Mitch the same guy as Baha? Because we have Baha's tutorial kicking around here somewhere. And back in my day, Baha's tutorial was all anyone ever got pointed to.

Thanks mizu, I think I get some
I like the way the ball moves. It's not realistic but it's nice to watch. The easing at the end was well-done, so that you really get a feel that there's a specific force acting against it. It's not erratic. But I think it might be better not to accelerate left again afterwards. Let it drop more or less straight (although there was still
some sideways momentum) and then you have a really good feel of a short-term weird force that stopped the ball in the air.
More generally, it's good practice to spend some time at the end (or after every completed frame if you're as neurotic as me) focussing on a single joint as you flick through the frames to check that it's not travelling in one direction for one frame and then travelling in a different direction in the next frame. Then repeat with the other joints in turn. It helps to cut down on shakiness like you have in the stickfigure after the throw. (I suspect you were focussing on the ball and forgot to animate the man until afterwards. It happens. This helps to fix it.)
You'll find
this tutorial useful for foot placement.
The only other thing is, try not to forget about the back joints. It doesn't seem like it should be necessary, but a stiff back always looks out of place on a stickfigure.
Here's my animation:

I think you'd also benefit from the
foot placement tutorial. The other major thing is easing. When the stick starts to move you need a few frames where it only moves a pixel or two, then build up speed. It's all about tricking the eye into seeing movement rather than a series of distinct images, and if you gently tell the eye where the stick is about to be then it will be ready for it.
You also have a stiffness issue. You should try to move every joint in every frame. It's (
slightly) less important for the target stick who's just standing there (although experienced animators would have him take a step backwards or something), but the stick who's kicking him should have movement in the knees, back, and elbows.
I don't think this one is as good as the other one. It looks a bit rushed.
It also makes it clear that you're not using Pivot 2.2.5. I spy overlap around the joints. I suppose this isn't technically a problem, but Pivot 2.2.5 is supreme and always will be :p.
Kind of a crappy first try, but eh, what the heck.

I have seen way worse first tries. I'd
made way worse first tries (well, one). You've understood the idea of showing more than just the start- and end-positions of the stick, which is always promising. I don't have much else to say to you that I didn't say to the other two - check out the foot placement tutorial and make sure you start off all movements slowly before they get up to speed (and make sure they slow down before stopping at the end too). Stiffness is also a thing, but I wouldn't recommend worrying about it too much until you've made a few more.