In the process of reviewing documentation for Orchestra.io, I found that it doesn't allow file uploads. Instead, it's recommended that Amazon S3 be used for file hosting. If you aren't familiar with it, S3 is an online storage web service that is part of Amazon Web Services (AWS). It provides access to fairly cheap storage through a variety of web service interfaces. This article will demonstrate how to sign up for an Amazon S3 account and use PEAR's Services_Amazon_S3 package to interact with S3 in your own application.
They walk you through the whole process - getting signed up at the AWS site, creating credentials, installing the Services_Amazon_S3 package (via the PEAR installer) and using it in some sample scripts.