draw a hexagon, with O at 1 vertex and a CH2OH chain by it sides and OH groups on every other C atom. the OH groups at the end of the hexagon adjacent to the the carbon atom with the CH2OH, faces in the opposite direction to that part while the OH group by the O atom is in the same direction as that atom, these (beta)glucose monomers join together with the CH2OH in alternate directions, where as in starch they face the same direction...
its really hard to explain verbally, there should be a diagram in most books..