Leaking Radiator

Hi,

The radiator in my apartment is leaking and I’d love to be able to fix it myself if possible. This is my first winter in the apartment so I have no idea if the leaks are new. Basically the leak comes out of the silver thing on the side. If I turn that thing one way the water comes out very fast. Turn it the other, the water comes out slower, but never stops. I have another radiator in this apartment that produces a steady stream of steam coming out of that silver thing. The steam does make a wet spot on the floor, so if it’s possible to fix that one too I’d love any advice. I can always call the landlord if this seems like a big job, but he is usually pretty slow about fixing things.

thanks!