How do I wire a series of lamps on a batten?

Question:I want to light my model railway

Answers:
You may have used an ambiguous word by mistake : SERIES

It very much depends on your supply and the
(power) type of the lamps

Assuming it is a 12 volt supply from a transformer and you have 12 volt lamps

Then run the wire to the one terminal of the lamp ( say the outer cap, if they are screw in types)

This wire then needs to be carried on to the outer cap of the next lamp and so on

Do the same with the inner contact; looping from one lamp to another

The result will be a string of lamps set out like a ladder shape ( they are in parallel - google to see a picture)

If you intend to use some other form of power supply then we need more information
such as what voltage is the supply and what lamps would you like to use