Upload Files within a specific folder from another page

Hello there,
I really like your plugin and it is what I need for my site.
But I also need to be able to guide the user for uploading his files. So I have separated pages that the user will upload files. From that upload action I want to be able to store that file in a specific BuddyDrive folder on the specific user’s Buddydrive space.

Could you assist me on that?
Is there an API or something else to use?

Thank you for your prompt reply.