Biology nervous system. HELP!!

Iv'e been on the nervous system and synapse/reflexes page in my revision guide for over an hour and nothing is sinking in, I just don't get the function and structure of sensory neurone, relay neurone, motor neurone, synapses and reflexes. I NEED HELP!! Can someone please explain it in an easier english and simple way.

Ok first think of sensory neurones as essentially the starting point. They can be present just about anywhere eg on your skin and there job is to detect the stimulus (the change in the surroundings). Say if you touch something hot, the receptors on your skin detect this and the first thing sensory neurones they do is convert the stimulus energy into an electrical impulse because only electrical impulses can be transmitted through the nervous system. Next the sensory neurones transmit the electrical impulse straight to the CNS - the brain which decides what to do based upon the impulses it has been sent. A relay neurone essentially connects to another part of the CNS transmitting the impulse only once the brain has decided what to do. Next the impulses are carried to an effector which is a muscle or gland via a motor neurone. In the case of touching something hot, this will be moving your hand away from the hot thing. So a synapse is a gap and this can be a gap between two neurones or even a gap between a neurone and a cell such as a muscle cell.The synapse has many important functions including not allowing the impulse from travelling backwards as well as filtering out low level stimuli (this just means things that won't have an effect on you/harm you). A reflex action is one in which the impulse does not reach the brain allowing the response to reach much faster. It does not usually involve a relay neurone. Eg if you stare at a bright light your eyes quickly move away from the light- this is an example of a reflex.