Welcome to Boston, Himaliketo!
If you have two days to be in Boston, makes sure you bring a really warm coat and an umbrella. Its gonna be mighty chilly and rainy over the weekend. If you are coming for the first time to Boston, then you are going to miss a lot of crowd in the city. Last couple of thanksgiving in Boston has been really quiet and empty...
Here is a very helpful link for you, you can pick and choose the things you would like to do. These are the 10 must-see things about Boston.
http://boston.citysearch.com/roundup/40085
Of course, you cant do all of them at the same time...so I would highly recommend going on the Ducktour. It is moderately priced but the tour guide tells you a lot about boston history, after all...this is a historic city. And they take you on the road and water..hence the 'duck'.
You should also go to the boston commons for a stroll...and there is a starbucks and dunkin donuts next to the park so you can warm yourself up. I recommend dunkin donuts just coz its based in MA and why not show some loyalty? If you make a left at any street off tremont street...and then make another left...you will get to the theater district. The opera house is beautiful.
I think the link talk about the freedom trail. You can just follow this (just look in the walkway, you will notice two lines of red bricks) trail and it will take you around. While you are in boston, dont forget to cross the charles river and hop over to Cambridge. This is where MIT and Harvard are and a lot of young crowd in the bars/restaurants. If you dont wanna worry about the parking, just take the T (thats wat we call the train) and it will stop at MIT and Harvard.
When you are here, please DONT MISS the Faneuil Hall market place. There are almost 30 stall like restuarants serving food and there is usually some fun stuff going. Here is the link:
http://www.faneuilhallmarketplace.com/
From here, its about 2 minutes walk to the boston harbor- just walk towards the east past the malls and Mariott. You get a great view of the city as well as the atlantic from here.
I hope you will enjoy this trip. It is truely a magnificiant city. I wish I could show you around, but I cannot dare to miss the black friday shopping spree :-) and I dont think my mom appreciates me showing a stranger around while she stays home (and she wont come along...she has tired of the city).
Enjoy!