Engaging/disengaging the clutch is a whole leg maneuver. The Z has a pretty light clutch. If your leg is getting tired, you must be riding it out a long time and slipping the clutch. You'll prematurely wear the clutch that way, but you'll figure it out in time.
The best way to learn how to drive a manual appropriately is to have a knowledgable person show you first hand. You can read all you want, but you'll still have a good chance of doing it incorrectly. There are some good YouTube videos which you may find useful.