Are you an EU citizen and lived 51 days in Helsinki? You can vote!
Or are you from non-EU country and lived 2 years in Helsinki? Yes then you can vote too!
Only thing you need is to have your identification with you when voting. If you vote in advance voting (29.3.-4.4.) you can vote in any voting point in Finland and your vote will be sent to Helsinki. If you vote on the actual election day 9.4., you need to vote in the voting station closest to your home. It is stated in the letter you have received in the mail.
Have you not received a letter about voting in the Municipal Elections? Contact Civic administration as soon as possible but no later than 16 days before the election.
More information about the elections in vaalit.fi