Take the clamp screw out, then put a screwdriver in the gap, where the screw was, turn the screwdriver to open the clamp, then slide the pole section in.Hope that makes sense.
wait for it now, ive snapped me clamp
A search would have brought up this recent post.See instructions from Alex Gardinerhttp://www.cleanitup.co.uk/smf/index.php?topic=125580.0