Walking using mouse

I get the picture, thanks guys..

screenx=640
screeny=480
Graphics3D screenx,screeny
speed#=.1
HidePointer
camera=CreateCamera() 
light=CreateLight() 
Dim cube(20,20)
For k=0 To 19
	For kk=0 To 19
		cube(k,kk)=CreateCube()
		MoveEntity cube(k,kk),k*3,0,kk*3
		EntityColor cube(k,kk),Rand(1,255),Rand(1,255),Rand(1,255)
	Next 
Next
PositionEntity camera,0,10,-10
PointEntity camera,cube(10,10),0
While Not KeyDown( 1 ) 
	xs=MouseXSpeed() ; see how far the mouse has been moved 
	ys=MouseYSpeed() 
	MoveMouse screenx/2,screeny/2
	;forward/backward
	If ys<>0 Then
		temp=EntityPitch(camera)
		RotateEntity Camera,0,EntityYaw(camera),EntityRoll(camera)
		MoveEntity Camera,0,0,-(ys*speed)
		RotateEntity Camera,temp,EntityYaw(camera),EntityRoll(camera)
	End If
	;rotate camera toward target
	If xs<>0 Then
		TurnEntity Camera,0,-speed*xs,0
		RotateEntity Camera,EntityPitch(camera),EntityYaw(camera),0				
	End If
	UpdateWorld
	RenderWorld 
	Flip 
Wend 
End