I use the little Buck Hartsook neck knife as a scraper for the fire steel to save my nicer knives wear and tear and because it’s just easier. The idea is that you scrape or carve off some of the metal rod with the knife, creating friction and a spark at the same time and throwing a gob of molten metal into tinder (you prepared tinder, right?), thereby setting it ablaze. It’s non-mechanical and works when wet, so you never have to worry about it running out of fluid or breaking.
This particular fire steel is super nice because that huge anodized aluminum handle makes it easy to hold and has a little waterproof compartment inside for some tinder; a button compass is housed in the lid. A starter this nice is serious overkill, but I like nice toys. If you don’t know what you’re doing and don’t need a solution this rugged, then it’s probably easier to just stick with a lighter.