Could you let me have a brief description of the legislative system in Finland? e.g. if it is a codified system and so on?

There is a presentation of the Finnish legal system on the www-site of the Ministry of Justice Finland http://www.om.fi/711.htm. After the ratification the law has to be published in the Statutes of Finland for to come in to force.
You can search and read the translations of the Statutes in the FINLEX database http://finlex.om.fi/ensaadkaan

The law in force is also found in Finnish and in Swedish in the publication Suomen Laki (The Laws of Finland) annually published by the the Finnish Federation of Layers.

If you are interested in the legislative work of the Finnish Parliament you will find some information on the www-site http://www.eduskunta.fi/efakta/index01.htm Besides the printed volumes the parliament documents are published in the internet database on the sites The Parliament http://www.eduskunta.fi/