My car has been leaking when it rains, I checked the seals and didn't find anything?

I have a Dodge Neon 01, I recently moved to North Carolina and realize that my car leaks when it rains. there is a puddle in the backside penger floor, but i can't seem to find where its coming from. I realized that its going into my trunk as well. Can anyone help as to where to take my car? it really creating a great amount of water damage. Thank you for your time