If you want to fix a TV bracket to a plasterboard wall there are certain things you need to know.
Settle on a spot on the plasterboard wall where you want to mount the TV. Mark the midpoint on the plasterboard wall and mark the bracket holes. You can use a spirit level to do this. If you plan to mount the bracket above the fireplace, then mark the centre of the centre of the fireplace on that wall and use a spirit level to draw a line vertically up to the midpoint of the TV bracket.
To get the accurate height of the TV bracket, you will need to measure from the base of the TV set to the top part of the TV bracket. Transfer the measurement you have taken to the chosen part of the plasterboard wall. This will ensure you get the TV at the height you wanted it to be.
Now, position the wall mount to the centre line at the right height. Mark the holes on the wall and use an appropriate sized drill bit to drill the holes. Use plasterboard wall plugs in the holes and screw the bracket to the wall using the screws provided.
When you are sure the TV wall bracket is firmly fitted in place you can fit your TV to the bracket.