Knead means to mix and work into a uniform mass, as by folding, pressing, and stretching with the hands: “She is in the kitchen kneading dough.”
Kneed, on the other hand, means to hit someone with a knee: “The woman kneed the knave and ran away.”
Last but not the least, need means a condition or situation in which something is required or wanted: “I need a shower because I am too unkempt.”