Electric line to subpanel
You'll have to run four conductors, two ungrounded (hot) conductors, one grounded (neutral), and one grounding (earth) conductor.

At the garage you'll have to install a grounding electrode (ground rod, etc.), and bond the panel and grounding conductor from the feeder to it.

You'll then have to isolate the grounded (neutral) bus bar and conductors, from the grounding bus bar, conductors, and panel.