First of all, you should hold the line in a way that enables you to throw it on a desired spot. Giving your cast line a perfect loop is the most important aspect for getting success in fishing.
After that, you should hold the rod in one hand and use your other hand to pull the line from the reel.
Now fly the line in the air which is also called casting the line. Whip it into the air by pushing flying the rod forward and then pull it back which will make the line fly in the air in a circle and you will get a better idea of where it will land in the water.
Hold the line in between your index finger and thumb and keep pulling the line from the reel in order to increase the distance of casting.
Flying line in the air is also called false casting which is very important as it enables you to accurately judge the casting distance and also assists in giving the fly cast a perfect loop.
While flying the line in the air you have to be careful because timing is very critical at this stage and you have to drop the line when it goes to the perfect length.
If you drop it soon in the water, the line will not spare enough time for the rod to load and you will not be able to hit a targeted spot or will miss the perfect loop.
Make sure you hold the rod tightly and throwing the line into the air with back and forth jerks that make the line create circle in the air and makes it easy to cover more distance.
While dropping the line into the water at a desired spot, you should bring the rod forward and let the fly drop into the water.
Make sure you do not let the line release from your fingers before it hits the surface of water as it will not help you in giving a perfect loop and you will miss your targeted spot.