In addition to the traditional border check, there are automated border control gates at Helsinki Airport which can check your passport rapidly and easily.
Further information
More information about Schengen countries, Nordic passport union and additional information about crossing borders is available on the web site of the Finnish Border Guard which is in charge of border checks on persons at border crossing points in Finland.
Entering Finland and visa requirements (Ministry for Foreign Affairs)
Applying for a passport and identity card (Police)
The video shows how to get through border check: