Maybe pcitures explain more:
pic 1 - enable remote access
Now click on configure and it will look like this
now in dashboard click on settings network

Now click on details it shows
IP Address is your mycloud ip address
netmask, usually 255.255.255.0
gateway is your router internal IP address
DNS 1 and DNS2 and DNS3 (if any) is taken from your router. These are the domainname servers (external IP addresses from your ISP, you find in your router).
 Example router DNS (router gets them from Isp)
Now forward the ports on your router (you may or may not need 8080 but i entered them anyway and forgotten about it)
As you see I have opened ftp (20,21), 8080 and 8443. The internal ip address is your mycloud ip address.
This is it. Test that your ports are open here http://www.yougetsignal.com/tools/open-ports/
If you have done all this and still does not work (make sure you have internet connection, 3g etc) then if your router has a firewall disable it. Make sure you enable firewall on your PC.
when using ftp (non lcoal network, from uotside)
Your ftp server will be your external IP address (your router external ip address it got from your ISP), the ftp client needs
ftp server
port 21
username
password
enjoy.