Read the instructions.  Don't put the cap the filling hole until it's all done...  it locks and u can't get it off readily.  Which is a good thing because it keeps the sand in it.   The tube for the umbrella shaft has three fittings  it fits sung and centered and it has a screw with a knob to tighten it in.    We had high winds and the umbrella was folded and fell over but didn't come out of the stand.