You should learn to operate emergency safety shower. You can do that by asking help of your supervisor or an instructor, who will teach you in person. There are also other ways of teaching. Some instructors prefer real life demonstration while others give preference to teaching through video, book or by conducting a test. You should know all the scenarios where use of safety shower is a must.
Make sure that nothing stands in the way and workers have an easy access to the shower otherwise things may get complicated. It depends on the size of your lab and the size of your emergency safety shower; some labs have one shower while many have more than one.
When you reach the safety shower area, pull the handle and the water will be abandoned. You should remove the clothing exposed to chemical substances to ensure maximum protection.
Clean the concerned area carefully. Remember that, there is no need to rush, so you should take the safety shower with in a comfortable manner. In most labs, you would have to pull back the handle to stop the water flow.
After you get rid of the chemical substance, you should call an ambulance to ensure that everything has been taken care of in a proper manner.