XNA how can i insert the jumping in my character?

Question

ks = Keyboard.GetState();

if (ks.IsKeyDown(Keys.Right) && position.X <= 680)

{

position.X += 2f;

currentAnim = forwardWalk;

Animate(gameTime);

}

else if (ks.IsKeyDown(Keys.Left) && position.X >= 0)

{

position.X -= 2f;

currentAnim = backWalk;

Animate(gameTime);

}

How can i make Up key for jump?