You have to find the studs, drill holes, make sure you have screws that are long enough (I imagine most wall mounts come with these, but never tried to actually wall-mount a TV), make sure the mount is level, then attach the mount to the wall, then the TV to the mount. That’s if you don’t care about exposed cables, and if you ever plan on showing your room off, someone’s gonna point out the lack of cable management (hurrr… Why aren’t the cables hidden?).

If you want to hide the cables too, then you have to cut holes in the wall, which means having some kind of saw. If you want the holes to look nice, then you need plates to go over the holes. Depending on the plates – whether they’re a basic, generic passthrough that you push cables through, or something more professional with actual sockets for dedicated inputs/outputs – you may need extra cables, one for each connection you’re wanting to route through the wall, plus extra cables to connect the plate behind the TV to the TV itself.

Now, if you don’t want to diy it, then you could pay someone to do it which makes it a lot easier on you, but now you’re spending cash to have someone do an easy but annoying and time consuming job for you.