Hi Karlos, welcome aboard. Try under the railway and road bridges, Bar Point and around Milsons Passage, Juno Point and Cowan Creek.
That should be enough to get you started and give you and your son some fun and a feed.
With the size of your boat especially if you have your son with you, watch the open waters around Lion Island, they can get big swells around this area (even around Juno Point).
You should be able to catch flatties, bream, tailor, jewfish, mullett and even the odd snapper among them, plus other species.
With you boat set it up how it suits you for fishing, and dont be afraid to try something different when fishing.
Make sure your son wears a life jacket when he is in the boat at all times.