The trail head is an easy parking lot, well maintained. It serves at the head for both the Liberty Bell Trail and the Arizona Hot Springs (these fork at a point - there's a map in the parking lot). Washes can be frustrating to follow, however this one tends to stay inside a narrow canyon with vertical cliffs, therefore giving you few alternatives. Also, it is clearly marked with happy blue arrows.
Once you reach the river, make a left. You'll soon find another arrow. Follow it (along with the other markers) to the springs. It'll be obvious when you come across a small luke-warm springs.