My bike clicks and it sucks I have a roughly 15 year old bike. When I pedal there is a loud click. When I coast the sound becomes louder and more frequent. The sound really annoys me. 

How do I fix this?
Your question does not provide enough information to locate where the noise is coming from. There are many things on a bicycle that can create periodic ticking or clicking. The best we can do is provide you some pointers to help track it down.

One of the most obvious things to do is try to recreate the sound when you are not on the bike. Hold the rear wheel of the ground and manually turn the pedals. Having someone assist you will allow you to move your head near the drivetrain and rear wheel and try to figure out where the noise if coming from. If the noise does not occur when doing this, the problem it might be associated with the front wheel.

If the sound persists when you stop pedaling but the wheel is moving, it's the wheels rather than the drivetrain.

You say the sound becomes louder and quicker when coasting. You may actually have two noise sources, one associated with the drive train and one with the hub or freewheel.