First of all ..... welcome to FSM aroberts
There are a couple of different things you can try. Strips of paper, metal foil, medical tape, and the list goes on. Cut it to the width you want, paint it, and apply it. Myself, I prefer the tape, it has a sticky back that adheres nicely to the object you're putting it on.
Hope this helps.
Happy Modelling and God Bless
Robert