how does a basic synapse work?

There are two types of synapse: chemical and electrical. A chemical synapse uses neurotransmitters to pass a signal from a neuron to another cell. Electrical synapses can pass electrical current to achieve the same objective - essentially, the synapse transmits voltage changes from the pre-synaptic cell to the post synaptic cell. You can find out more here: http://www.yorku.ca/lsergio/4505_Topic3.pdf