How do I install it?

oh ffs... seriously? This is not a chatroom put a little more effort into it when you post on the forums.

First of all this question has probably been posted multiple times, so a quick search would have gotten you there.
Second of all, what did you do yourself trying to install it? By the looks of it nothing since the freaking thing comes with a installer...

Can't open files.

first you cant install it and now you cant open files?
Oh my bad it doesn't come with a installer it is all in a zip file so the only thing you had to do is unpack it at a location of your own liking...

Don't know what is wrong. I click files, internet search come up.

seriously dude you are not helping anyone here... what files are you clicking? What did you already try...

I try to extract files, they don't show up. I want to use Dragunov, but need Slab6 to open files. And I can't open Slab6 files.

if you want to use someone else's mod you just need to place the files in the correct folder...as far as editing them goes... I wouldn't try that since this is causing you enough trouble already...

+1 for Creesch

Don't worry, problem over.