Mesa connection issue

I can't save the interfaces file with the changes. I'm using mousepad.

you need to be root to edit most system files
so
sudo mousepad

Ok, thanks. I'm only a few months old as a linux user. I made the interfaces file changes.

I now get an error stating that the network is unreachable.

OK what does
ip a
report now?

and whats in the interfaces file?

Here are the files

Try this:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
address 10.10.10.100
netmask 255.255.255.0