If you just need to be able to fetch files, and you're okay with them being publicly accessible, the only API you need is HTTP. All objects uploaded to DreamObjects are accessible at a URL of the form:
You can use any HTTP library to make such a request (including a web browser - try clicking that link!). No special headers are necessary.
If that doesn't do what you need, or if you need further information, please see the documentation at: http://docs.dreamobjects.net/ — libraries are available for a number of major languages. Let us know if you need any additional assistance.