You might need to install other software to open this address.

I am trying to use external links in sites like kde-look to install packages on my linux mint 18 KDE system. I have install the software xdgurl as require but I recieve this erro message when I try to install a file or program The address wasn’t understood Firefox doesn’t know how to open this address, because one of the following protocols (xdg) isn’t associated with any program or is not allowed in this context. You might need to install other software to open this address.