Lettusbee, or lettuce bee, is right. They do come with directions. And if they don't, then you can print them out from bushwaker's site ( Lettuce man ^^^ up there posted the link for ya.
But this is a very easy thing to do, tho it may cost more than your mortgage but trust me, it's worth it. Ok so the reason I got my flares was to 1. cover my rust 2. to make my tires not toss up so many damn rocks. Well only one of those ended up working, considering i moved from 33x12.5's to 36x15.5... yes 15.5.
So the first thing I did was cut my rust off with an angle grinder (only on 2 of the fenders). If you have rust I suggest you do the same thing and just cut it off completely, sand, prime, and paint it. If not, you really don't have to do anything to prep it before you throw the flares on.
Bushwacker will send you both screws and pop rivets that you can use. I suggest using the screws because there a hell of allot easier to install and MUCH easier to take back out. They will also give you a big wrap of rubber that you will use as a buffer between the flares and the body. Cut the rubber long enough to make it across the tops of each fender ( and I'd leave a little extra on the ends to work with).
Make sure you line the flares up against your wheel wells the way you want them, with the rubber underneath. When I did it, I had 2 other guys hold it up while I eyeballed it and tried to find the sweet spot for where it would fit.
Then you will want to screw the screw in with the little white plastic snap fastener (this is what you will use to cover the screws). It should look like that^^^. And then snap on the black caps.
And for the rear flares... They are custom made to fit for the stock back bumper (which I am obviously lacking).
So I'm clueless to how well those fit over it sorry

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This goes for all for of the fenders. I'm sure the actual directions are a little better than mine, but it's always better to see pictures and stuff.
Here's how they look now tho. Good luck!