Usually mounts come with a bag or two of screws, so look around and see if you can find where you (hopefully) put it. I would guess M4 screws for a small TV. Lengths are a bit of a guess, since the thickness of mounts varies. They usually include some washers too. I usually hand turn the screws into the TV (without mount) to make sure they can easily go in further than they will once the mount is on, then unscrew and put them through the mount.
I would have to guess that your TV weighs under 10lbs, so it won't take much to hold it. People put 10lb pictures on the wall with just a tiny nail into drywall.
Banned but back. Because why not?