A crystal by itself does not oscillate.
It's a resonant device something like a bell or a guitar string, and something needs to activate or "excite" it, to get it started and keep it going.
You can buy a crystal oscillator
for 3 or 4 times the price of a crystal alone. (That example is the wrong frequency). You'll probably still need a frequency divider. These have 3 connections: +5V, ground, and output. (There is usually a 4th unused pin.)
Most circuits you'll run-across will either use one of those oscillators, or in the case of a microprocessor/microcontroller (like the Arduino) the oscillator circuit is built-into the chip, and an external crystal is used. You'll almost never see a crystal oscillator made "from scratch".