Start with positioning yourself properly. The proper way to stand is to keep your shoulder straight wide and with both feet open towards direction you are aiming to throw.
Keep the fishing rod or pole in level position to the ground with lure spread out towards the point you have marked to throw your pole. Just hold the rod and do not throw or leave it on the ground.
After standing firmly, raise the fishing pole or rod towards the sky in an angled position. Do not lift too high and keep thumb of your throwing hand under the reel. You do not need to hold the pole at the same position for a longer period of time but it is explained only for defining the position how you should hold the pole just before casting it.
You will then need to draw your pole towards your back. Keep your elbow in the bending position until your hand is parallel to the rod. The tip of the rod or pole should be just behind you.
Next step is about casting the pole or rod actually. After drawing the pole with tip of it just behind you, push down the reel and forward your arm with a swift movement, extending your hand out towards the water. When you snap your elbow slightly forward, the tip will be extended out in the water with a small jerk.
Remove your finger then from the reel and let it loose. The rod should be at the same position it was just before you drew it to the sky with an angled position. It might appear making no difference to you, but as you continue fishing on a regular basis, you will start realising that it does make sense to cast a fishing pole or rod properly.