The monomer of polyvinyl chloride is - so don't say you never learnt anything from the internet - vinyl chloride. This has a molecular formula of C2H3Cl, and is more correctly called chloroethene.

It looks like this:

Cl       H
  \     /
   C = C
  /     \
 H       H
PVC, its addition polymer, consists of macromolecules which are simply long chains of chloroethene:
     Cl   H  Cl   H  Cl   H
      |   |   |   |   |   |
- - - C - C - C - C - C - C - - -(with thousands of repeats)
      |   |   |   |   |   |
      H   H   H   H   H   H