where i should put this code to script.i make like this. 
  
local x, y, z, x1, y1, z1 
local fpcam = false 
  
bindKey( "F2", "down", 
   function() 
      if fpcam then 
         setCameraTarget(getLocalPlayer(), getLocalPlayer()) 
      end 
      fpcam = not fpcam 
   end 
) 
  
addEventHandler("onClientPreRender", root, 
    function() 
        if fpcam then 
            x, y, z = getPedBonePosition(getLocalPlayer(), 6) 
            setCameraMatrix(x, y, z, x + x1, y + y1, z + z1) 
            dxDrawImage(screenWidth/2-10, screenHeight/2-10, 20, 20, "images/aimer.png") 
            local tarX, tarY, tarZ = getWorldFromScreenPosition(screenWidth/2, screenHeight/2, 30) 
            setPedAimTarget(getLocalPlayer(), tarX, tarY, tarZ) 
  
function getPointFromDistanceRotation(x,y,dist,angle) 
    local a=math.rad(90-angle) 
    local dx=math.cos(a)*dist 
    local dy=math.sin(a)*dist 
    return x+dx,y+dy 
  
if getControlState"left" or getControlState"right"  then 
  local _,_,Zrot=getElementRotation(getPedOccupiedVehicle(getLocalPlayer())) 
  wx,wy=getPointFromDistanceRotation(cx,cy,((cx-wx)^2+(cy-wy)^2)^0.5,Zrot) 
end 
        end 
    end 
) 
  
  
  
addEventHandler("onClientCursorMove", root, 
    function( _, _, _, _, wx, wy, wz ) 
        local cx, cy, cz = getCameraMatrix() 
        x1 = ( wx - cx ) / 300 
        y1 = ( wy - cy ) / 300 
        z1 = ( wz - cz ) / 300 
    end 
)