The producers would like to bring it to a theatre near you, but this non-commercial endeavor is being marketed in an unusually way. Basically, they need 1,500 people in a city to express interest via the film's website - click here - in order to arrange a local showing.
Here's a brief description, from a review in Foreign Policy in Focus (Estonia's Singing Revolution):
In a remarkable new documentary, The Singing Revolution, filmmakers Maureen and Jim Tusty tell the little-known story of the Estonian people’s nonviolent struggle against decades of Soviet occupation, culminating in that country’s independence in 1991. The movement played an important role in the downfall of the entire Soviet Empire.
The title refers to the use of Estonian folk songs to assert a collective national identity that rejected Soviet Russian domination. Here's the film's trailer: