Hello there,
I have a light and switch on the sid of my garage and would like to add two more lights and a swtch off the same power source. Could you please show me on a drawing ow this would be done. Thank you for all you help.

Pick up an inexpensive book at a hardware store or home improvement store on electrical circuits. It will have diagrams and pictures to help you much better than any answer here. You will be dealing with series / parallel circuits.

Difficult to answer you because we have no idea as to how the original circuit was wired . Do you know the difference between through wiring and a switch loop? Take the cover off the switch and tell us how many wires, colors and how connected.

You need to help us quite a bit more.

Adding the lights to the existing circuit is fairly straight forward. It's a matter of adding the lights to both the source black and then tying all of the Neutrals (Whites) together.

However, if your intent is to control the operation of the lights from two locations, then the process becomes more complex.

The wiring has to change between the switches (3 wire) Two of which are called runners the third would be a power source.

The type switches would also have to change. You would need to replace the standard snap switch with two "Three way" switches.