Faucet won't shut off
 

I can't get my faucet to shut off, just keeps running. The knob just spins, any way to shut it off and/or fix it?

Is it just the handle that spins. If so install properly to seat and move stem.
Unscrew the screw that hold the handle to the stem

If the handle rotates the stem and it spins completely around for many, many turns, the stem needs to be replaced. But if it rotates and then stops that is normal. If the leak is small replace the round washer/seal on the bottom of the stem.
Never crank down hard on a valve to seal. it will rarely get better if man-handled! Should need minimal pressure to seal

The stem is the shaft for the water valve, and seal.

Obviously water should be turned off if hooked up to street water!