Files in salesforce can either be Chatter files, Content, Knowledge, Documents or Attachments.
Each of them have different objects to store them. You can find which object is used for each of them from the SOAP API developer guide: https://www.salesforce.com/us/developer/docs/api/
Once you find the object name, you can query using the REST API by forming the query as in this example: http://danlb.blogspot.sg/2011/02/salesforce-rest-api-query.html
Each of them have different objects to store them. You can find which object is used for each of them from the SOAP API developer guide: https://www.salesforce.com/us/developer/docs/api/
Once you find the object name, you can query using the REST API by forming the query as in this example: http://danlb.blogspot.sg/2011/02/salesforce-rest-api-query.html