How to open Finale files in MuseScore
To transfer your sheet music collection from other music notation software, use MusicXML. MusicXML is the standard exchange format for sheet music. Finale users can download a plugin to export their sheet music to MusicXML files and then import these in MuseScore via File -> Open.
Most Finale versions (incl. the free Finale NotePad 2012) come with MusicXML export, but if it doesn’t, or if you want a more accurate export,
download the Dolet plugin:
Official download page: http://www.musicxml.com/dolet-plugin/