What? That just sets collision on you moron Ali.
For the screen:
if xBall<0+(ballRadius/2) then xMove = 5
if yBall<0+(ballRadius/2) then yMove = 5
if xBall>640-(ballRadius/2) then xMove = -5
if yBall>480-(ballRadius/2) then yMove = -5
ballRadius is the size of the ball, I just checked you code and I assume its 8 so use that. Each loop you'll need to put that previous code, then this to update the position:
inc xBall,xMove
inc yBall,yMove
then you'll need to draw the ball:
Just use that kind of technique and it should be easy. I'll post again explaining how to make it bounce of the paddles in a sec.
CURRENT PROJECT: Chaos Hizzle Demo