Hi Rahul, Hope you are doing good. Places to visit in Andaman are Havelock island, Radhanagar beach, Viper island, Baratang island etc. Dont forget to experience the magical scooba diving there. Please hit upvote if you liked my suggestion. Thanks in Advance.
If you are going for a 4 day trip, I would recommend exploring Port Blair in Day 1
Things to see in Port Blair
1. visit the museum
2. you can go to Ross Island, also visit the aquarium on the way
3. visit Saw mill of port Blair
4. see Cellular jail in night Day 2
Go to Havelock Island and enjoy the day in beach
You can also go to elephant Island and watch the corals. Day 3
Baratang Island and Limestone caves. Day 4
buy some souvenirs and you can visit wandoor beach, which is a cinema shooting spot.