if i remember it right... it's polar when the shape is non-symmetrical
and non-polar if it's symmetrical.
.....Cl
.....|
H - C-H
.....|
.....H
i think above example is not symmestrical becuz there is Cl instead of H.
if it was H, then it would be symmetrial thus non-polar.
but it's not symmestrical so it's polar.
It depends on what the central atom is attached to, as stated in examples above. CH3Cl is polar but CCl4 is not, because even though Chlorine is electronegative and hoardes electron density, it pulls it in equal and opposite directions, not a particular direction in 3D space.
There is also trigonal pyramidal, which may or may not be confusing you, as in the case of NH3, which has a lone pair.