It should be pretty straightforward, once you know the name of the package you want to install.
“apt-get install <package-name>”
If you’re not running as root, you’ll need to sudo
“sudo apt-get install <package-name>”

Well i dont seem to have any outbound connection, this is my respond :Reading package lists… Done
Building dependency tree

Reading state information… Done
E: Unable to locate package

ive tried to update repository sources.list with no luck

Check package name. If it is correct apt-get must be work.
N yes dont forget to put sudo if not root user.