Hi Sonam,
It is very simple: place your left hand on your solar plexus. Raise your right hand with the first three fingers raised, and the final two lowered. With this hand, Make the sign of the cross over the plant, and pray "In the name of the Father, the Son, and the Holy Spirit," and make a circle around the cross you made. Of course, this should be in addition to prayer to your Innermost for help commanding the elemental.
“Nothing is easier than self-deceit. For what each man wishes, that he also believes.” —Demosthenes
"Do not worry; cultivate the habit of being happy." —Samael Aun Weor