To get the best help for your situation, first answer the questions on the Preliminary questions page.
Fill out a divorce application (in Finnish) and send it to the District Court.
Submit the divorce application to the district court of your place of residence using Suomi.fi Messages.
If you file for divorce together, send the same application from both of your Suomi.fi Messages accounts to the District Court of the place of residence of either one of you. Both of you should send the application on the same day.
You can also send the application to the District Court by mail.