This piece – A guide to Arvo Pärt’s music | Music | The Guardian – is a fine introduction to the music of Avro Pärt. This quote sums up his work well:
The success of Pärt’s work – the repertory of choral works he has composed over the last four decades, the instrumental works, even the new symphony he composed in 2008 – is, I think, much more than simple popular acclaim for a composer who uses some familiar chords. Pärt told me that what he wants his music to express is “love for every note”, and in turn, communicate the spiritual power that he sees as music’s essential purpose. Pärt is too modest to say that he has achieved that, but for the listeners who love his music, it’s an irrefutable truth.
There are lots of places to find his music, including YouTube. Here’s one of my favorite pieces, Spiegel im Spiegel
Enjoy that piece, and hopefully enjoy many hours listening to the music of Part.