You will need...here.
NB: Make absolutely sure the fairy lights you use don't give off any heat (which is true of some LED lights), otherwise - not wanting to panic you or anything - the whole project could catch alight. And possibly your front room.
Very easy...Not to mention very straightforward. You need to be reasonably dexterous with pliers and jewellery wire and that's about it!
TimeAbout an hour, depending on how many lights you have to cover.
Strike a light!
Repeat this process with the rest of the lights and bottles.