[ubuntu] Installing Mono for C#

Hi I have tried to install MONO by "Xamarin" on to my system which is ruing Ubuntu 15.10. My first attempt was via the "Ubuntu Software Centre" which failed. So I tried directly from the MONO web site which also failed. So I tried to un-install the software but it now retus the following error message:

"This error could be caused by required additional software packages which are missing or not installable.
Furthermore there could be a conflict between software packages which are not allowed to be installed at the same time."

How can I resolve this issue and install the MONO software.

Regards
Stan