Is there any where i can park my car for on the weekend if i did not want to take my car on to the ferry?

yes

Where do you park your car on port Jeff side

Consider taking Metro North train to Bridgeport and leave your car up (or down) the line - e.g., New Haven or Stamford in the station garages). It's a short walk from Bridgeport train station to the ferry terminal.

Yes, there are several parking garages within walking distance of the ferry on the Bridgeport side. I've parked overnight without issue

If your are in Port Jefferson you can park your car for the weekend but in Bridgeport there is no overnight parking because of vandalism.