Officially you cannot. This has been discussed previously:
http://community.wd.com/t/can-only-download-pictures-via-link-not-view-in-browser/170509
http://community.wd.com/t/using-my-mycloud-to-host-my-blog-photos/155738
http://community.wd.com/t/direct-link/145919
Unofficially it may be possible using a third party OS (depending on single bay My Cloud version) or SSH/FTP.
http://community.wd.com/t/clean-os-debian-openmediavault-and-other-firmwares/93714