Put a new battery in, and it still wont crank over. Why?

I checked the battery cables and terminals, fuseable link and anything around battery, all are good, clean and tight, but still get nothing.  It makes a click sound at the battery area when I turn the ignition and a kind of hiss noise comes out around the bottom of engine, which led me to believe it's the starter that is trying to crank over.  I could not locate the starter for this truck.  Anybody whose had this problem, please help; desperate for wheels to and from work, bus sucks.  Thanks.