draw a diagram of the water molecule. then draw where the electrons are to show it's covalent.
so does that mean its lewis structure, which would be:
..
H- O -H
..
but where would the electrons go?
Many pictures of H2O here:
http://images.google.com/images?hl=en&q=%22water+molecule%22&gbv=2
but which one shows the electons
http://www.promotega.org/UGA06004/covalent_bonds.html