Ed Pawlowski wrote

I want to wall mount our 55" TV. I see mounts from $12 to $60. I don't
want or need articulating, just flat and maybe the ability to tilt.

But horizontal articulating does make it easier to mount
the TV and can be handy to change a cable etc too.

I see you mount on the wall and a part on the TV. How do you put them
together?

You attach the mount to the wall. Pull the plate that bolts
onto the back of the TV out, screw it onto the TV, push the
TV back against the wall. Tilt it to the angle you want.

I will have help lifting it in place.

Yeah, its too big to do alone.

I also know exactly where the studs are. I have a photo of the framed
wall when it was being built and a stud is to the right of a box on the
wall. No guessing there.