Re: I need help with my kittens!!!!!!
Just a bit of kitteh psychology/language:
1st kitten, who is very comfortable in his home, sees new kitten and thinks: "Play buddy!" (or mating behavior)
2nd kitten, who is brand new to the home, everything is new/scary, now has this rambunctious kitten leaping on him. I'd hiss, too.
You may want to seperate them, put the new kitten in a room of his own with the necessities (food, water, litterbox and sleeping area) and visit him often to reassure him and get him comfortable enough to play. Eventually, he will show interest in exploring, and you can let him out to explore at will, you sort of following along as reassurance for him. You may also want to put #1 kitten up, for the first few forays the new kitten takes in the home.
Also, check out "new cat introductions" on how to properly introduce two new cats/kittens with as few hiccups as possible.
Best of luck!