Finland is part of the Schengen Area and has therefore jointly agreed the rules concerning the movement of third-country nationals in their territories and decided which countries’ citizens are required to present a visa. Detailed information on country-specific requirements and country-focused travel documents accepted by Finnish authorities can be found here: um.fi/visa-requirement-and-travel-documents-accepted-by-finland
A valid passport or other travel document accepted in Finland is required when visitors enter the country. It must be valid for at least three months after they plan to leave the Schengen Area, and it must be less than 10 years old.
Detailed instructions to applying for a visa can be found here: um.fi/visa-to-visit-finland
The instructions vary depending on the country of origin, and the visa fees depend on the application form. The regular visa fee is 80 euros, other fees are listed on the website linked above. The application forms can also be reached from the website. The application can be submitted at the earliest six months before the intended visit, and latest 15 days before the visit.