Start by pointing DF Code at a repository already on your machine — it'll confirm it's a real git repo and pick up whatever remote it already has.
Create a new workspace, give it a name, and attach that repository (and a Domain, if you've already written one down for it).
Activate the workspace. This sets it up with its own isolated checkout, so nothing it does touches your main copy of the code until you're ready.
Open a thread, describe what you want, and send it. Watch the response stream in live, with any resulting change shown right there as a diff you can review — see Diffs, history, and editing files directly for more on that.
Once this feels natural, look at Agents & the Conductor for running work on its own schedule, or Build a Watcher / Addresser strategy for wiring up more than one agent that hands work to another.