You can’t do it with FTP. There’s no easy way for two users to completely share a directory. You’d have to go with creating a Group, and that user will have to use SFTP so they can get to that directory. Or you can re-create that directory in their home space, and Re-map it, but you’d still have to create a Group so you can enter his directory:
As I look at the albums directory (neat pictures, by the way), it looks like you’re using ZenPhoto. I use Gallery (also a One-Click install) and it allows much more flexibility with permissions.
What is it you hope to accomplish?