A link to what you bought would be a big help. There are crystal oscillators in metal cans and there are just crystals in metal cans. Each can have three leads. Most crystals have two leads, but the can may have a ground wire.
A crystal is NOT and oscillator. An oscillator requires feedback to produce oscillations. The crystal allows oscillations on just one frequency, usually. You do not supply any feedback to the crystal.
I am sure you Googled crystal oscillator. Did you find a circuit that looks like what you described?
Paul