Neurons, or nerve cells, are the basic units of the nervous system. Now, neurons are lined up next to each other, kind of like train stations. In between each station there is a gap. It is in this gap that neurotransmitters flow. This explanation is very basic because there are so many more parts of the neuron, but I'll just use the basic stuff to get the picture across.
Neurotransmitters are chemical substances that transmit information from one cell to another.
The process is detailed so just trust me on this. There are two types of neurotransmitters- those that inhibit, or stop, and those that excite, or make it more likely that something will happen. Okay, you've gotten this far and it isn't too scary. The rest is a breeze. I mentioned before two neurotransmitters, dopamine and norepinephrine.