I want to network map Mycloud Pro Series from my Office into my Home

hello guys, Im sorry Im kinda noob on setting my [My Cloud Pro Series PR4100], I want to set or create a network path from my home pc to my cloud from my office. So basically my PR4100 is in the office and I want to attach it to my Home pc or any PC outside my LAN. its like the samething WD Discovery doing to My Cloud Home Device, but here in My Cloud Pro I don’t know what I did wrong.

thanks in advance if someone can provide a clear explanation how this one works. Since WD Discovery can not detect or will not detect My Cloud devices directly.