I am new to Ubuntu and probably done something dumb. I installed Mate 15.10 on a Gateway E265M. Connected via wireless. After playing and reading for a Day I Wanted to install Wine to see if any of my Dotnet app would run.
I tried to install Ap Grid… But get an error “Requires instillation of untrusted packages”
Not sure where to go from here.
Dave
Hi Dave, welcome to the community!
It sounds like the "key" used to authenticate packages might be missing from your system. You can try to update the package lists which is a common way to fix issues like these.
The quickest way is through a terminal. Press CTRL+ALT+T and type this command:
sudo apt-get update
Then enter your login password, note that you won't see any asterisks when you type this.
Then try installing AppGrid through the Welcome program again. If there's an error, the output from the terminal will let us know precisely what went wrong.
In a future version of Ubuntu MATE (16.04), they'll be a button to auto-magically fix such issues without needing to open a scary terminal. 
The alternate method is to install AppGrid manually as would the Welcome program would do:
In the terminal, enter these commands:
sudo apt-add-repository ppa:appgrid/stable
sudo apt-get update
sudo apt-get install appgrid
Thanks for the welcome and such a quick response.
That did the trick. 
I appreciate the help. I can see I have a long way to go.
Dave