If you read the answers in the link below, you will understand how to do file upload and save to server with emberjs:
File upload with Ember data
In the answer provided by 'Toran Billups' in the link above, the lines below, which I copied from his answer, do the saving to server:
var person = PersonApp.Person.createRecord({username: 'heyo', attachment: fileToUpload});
self.get('controller.target').get('store').commit()