I have a switch box that will hold 3 different switches. Each switch will control a different light.
One 2-wire power supply entering the box. How do I wire the 3 switches to control 3 separate lights

Try this:

https://www.askmehelpdesk.com/attachments/electrical-lighting/39229d1329993049-help-asap-3-gang-switch.jpg

I have a switch box that will hold 3 different switches. Each switch will control a different light.
One 2-wire power supply entering the box. How do I wire the 3 switches to control 3 separate lights

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Im assuming your black wire is my "red wire" running from the power source which I have screwed into the common (C) of the light switch, then another red wire connects from (L1) into the ( C ) of the light bulb.

The white wire would possibly be my "black wire" which I have followed your diagram by bining them together.

All 3 light sockets are positive and tested as being live by using a electrical circuit tester.
But somehow when the light bulb is inserted and turned on at the switch, light bulb does not work.
Have I missed something out, please help

Thanks Ropa

I think what you are saying is that you are not in USA.

You have been provided two wiring diagrams, and either should be sufficient for you to connect the three switches and three lights.

This is not that hard.

If your not in USA or Canada, that would be good to know.

We need to know your location, the voltage you have, and the color codes you have.

I live in New Zealand. The voltage is 240 and the colour codes are red wire (positive live) and black wire (negative).

Do you possibly have a wiring diagram that illustrates the red wire being connected into back of light swtch then continuation of red from back of light swtch into the light bulb socket.This is so I know what hole to connct wire up to in light swtch.

Thanks

I can remake the drawing showing your wire colors, and will do so if you desire.

If you have, as your post indicates, substituted your red for my black and your black for my white, then you have correctly translated the drawing.

I, of course, do not know the wiring practices of New Zealand. Therefore, I am hesitant to say more. I will say just from simple logic that I don't think your problem is the connection at the light fixture.

The switch that we would use in this situation would be a simple single pole switch. It would have two terminal connections. It doesn't matter which terminal is connect to the incoming power and which terminal is connect to the out going power. The switch doesn't care which way the current flows through it. It only cares that there is a connection or there is not. You said that your switch has a common and an L1 connection. Again simply logic makes me think that if there is an L1 there should be a L2 terminal. If so that would be a double pole switch. There would be a connection between common and L1 when the switch is in one position and a connection between common and L2 in the other position.

If that is the type of switch you have, it work just fine, you simply connect to the common and one of the other terminals. If the switch doesn't work in one position, it will work in the other.

Likewise at the light fixture there should be two connection points. As far as the light bulb is concerned it doesn't care which wire is connected to which terminal. For personal safety our practice is to connect the hot (live) conductor, (our black your red) to the terminal that connect to the center of the light bulb and the neutral (our white, your black) to the terminal that connect to the screw shell (the part you use to screw the bulb in). Again this is for personal safety only. The light bulb, just like the switch, doesn't care which way the current flows. Therefore no mater how you connected the two wires the bulb should burn.

While there is a positive and a negative voltage in a DC circuit and the current flows in one direction, there is no such thing as a positive and negative in an AC circuit. By definition each wire is positive for halve the cycle and negative for halve the cycle.

We are two people separated by a common language. It may be your practice to refer to the hot or live as positive or negative, I don't know. Or it may be what appears to be a very limited knowledge of electricity and wiring, and I don't say that to be unkind.
I suggest you find someone to assist you that is familiar with wiring. That should not be difficult, this is about as basic as you can get.