How does electronegativity cause the polarity in water and, ultimately, enable water to form hydrogen bonds between other water molecules?

Oxygen is more electronegative than Hydrogen 
                                  So . . . 
When the two form covalent bonds, oxygen pulls the electrons closer and farther from hydrogen
                                   So . . .
The water molecule is polar, with oxygen more negative and hydrogen more positive.
                                   So . . .
Since opposites attract, the more negative oxygens attract the more positive hydrogens of other water molecules, forming the hydrogen bonds.

They are all full and don't need any more electrons in there outer shell.

Decomposition is the cycle at which bacteria breaks down any organic material into the soil