Actually, if you just click the "Current" box in the Inspector on the camera, that should do it, i believe, if you’re trying to get it to move WITH your player object. If you’re trying to move it relative to the player (independent camera movement detached from player movement) then it’s just a matter of changing its position along with the code. Something like:
Func _input(event):
### your action code here
#Camera2D.position.x +1