I'm guessing your problem is with the Hammer Throw, but you say the Javelin Throw AND the Hammer Throw (toss). If it's the hammer, you'll notice it changes color at one point every time it hits a certain point, which is the correct time to press the button to release it. Of course, you need some momentum to throw it long enough, so it's tougher. And as with most things, an approximate 45 degree angle is what you want.
I forget the specifcs of the high jump, but you press the button once, when close, release it, then I THINK you have to do that two more times during the jump. I'm sure the details are easily found in a search, I just can't remember.