i have a Player class wich works fine, but i don't know how i can make someone jump and then land on the ground again. also, how do i make sure you can't fall through the ground.

Thanks in advance.

Hi, you can create a physical body for your character model in the editor, then it should not fall trough. For the jump animation, you can import the animation, link it to the player object and start it in your code upon a keypress for example.
Make sure to set the gravity and enable physx in the code also. You can also take a look at the tutorials, since I think there are some also including a jump animation.
Good Luck