Every casting stroke is a smooth acceleration followed by a stop.  Acceleration means that the rod pulls the line all through the cast.  The cast is complete when the rod stops.  The acceleration bends the rod and loads it like a spring. During acceleration, the rod bend increases, when it stops, the rod straightens propelling the line to where you want it to go.

Many experts liken this to flicking paint off of a paintbrush.  Most people can understand this concept making it easier to learn a basic cast.  The better the stop is, the more effective the cast is because the energy transfer from the rod to line is more efficient.

The line will always follow the rod tip.  When the rod stops, the line will go in the direction the rod tip was going in when the stop was made.  Thus, if you want your line to go straight, make your rod tip go straight.  

There are two basic stances you can use when preparing to cast.  The orthodox stance calls for you to put your foot below your casting arm shoulder and slightly in front of the other foot.  For example, if you are casting with your right hand, the right foot should be slightly in front of the left foot.  Your feet should be slightly apart, your body relaxed and comfortable.  You should be able to transfer body weight easily between the feet during the cast.

If you use an open stance, your feet will be placed the opposite way of the orthodox stance.  If you cast with your right hand, your right foot will be placed slightly behind the left foot.  This type of position is used mainly for distance casting allowing the caster to turn and watch the back casting without moving or turning the shoulder.