Some schools in Helsinki give bilingual instruction (kaksikielinen opetus). In that case, the instruction takes place in Finnish and another language. The pupils are selected based on an aptitude test. Advance preparation for these tests is not possible. You can register for a test by filling out an aptitude test form. You can get this form from the school's website.
Helsinki also has private schools and schools run by the state where you can study either entirely or partly in a foreign language. The education usually starts at the school's own preschool (esikoulu) or daycare (päiväkoti). Some of the schools charge a tuition fee.
The pupils are selected based on an aptitude test.