I put in the command “sudo apt install snapd” in the terminal and once it finished it read “E: Unable to locate package snapd” Is there another way to get snapd my version of Ubuntu is 15.10. I already used the command “sudo apt-get update”.
Ubuntu 15.10 is long gone and archived 
try following:
https://help.ubuntu.com/community/EOLUpgrades
to upgrade to a supported Ubuntu Release …