Hey, welcome to Finland! :) I don't know if you are still in Helsinki, but if you are, here are my suggestions.

Go on top of Tähtitorninmäki, it's close to city centre and the views are pretty nice over the city and the sea. Eat creamy salmon soup somewhere, like at the old Market Hall, and go visit the "prettiest street in Helsinki" Huvilakatu, if you like Jugend architecture. If you want something super special to write home about, go have a swim at Allas Sea Pool, you can swim in a warm pool outside, while it's sub zero temps around you.