Head south from the Arica Road Trailhead. This trail gradually climbs until meeting up with the beginning of the West Butte Trail. The trail then climbs a bit more, traversing the side of a small hill. You'll reach a saddle but then climb some more. Then it is a descent to the far end of the West Butte Trail at the sound end of Casa Grande Mountain Park. Most trail junctions are fairly well marked, so it's pretty easy to stay on the right trail.