Wiring second breaker panel
If the house is detached you still need ground rods or a concrete encased electrode. You didn't answer ThreePhaseEel's second question. 

Either way, The ground wire gets attached to the ground bar. All grounds and neutrals are kept separate on their own bars. The green bonding screw for the panel is NOT installed. Discard it.

There are several other questions on this site regarding sub-panel installation. Like here.

Good luck!