I am 36 and stepped on a rusty tack that went as far as it could into my foot do I need a tetanus shot? : (

Tdap recommended. Tetanus shots are good for 10 years but if the injury is 'dirty' then >5 years is the norm. However, the adult tdap is recommended now to cover tetanus and whooping cough. The other worry with a puncture wound is the risk of infection . I hope you could clean the wound with soap and water. If any redness/pain/swelling you should get seen because of risk of bone infection (osteomyelitis).
Yes, you do. Please go and see your doctaor as soon as possible.