Upgrading a package, or a set of packages, is just as simple as installing them when you use apt-get. Once you are ready to upgrade to the new version of Midnight Commander, simply enter the command:
and the package will be upgraded.
If you want to upgrade the entire system, leave off any package names:
apt-get upgrade
will upgrade all of the packages on your system.
This command will normally work just fine, but under circumstances where the dependencies have changed on an upgraded package, this command doesn't always do the right thing. To deal with these dependency problems, apt-get provides the dist-upgrade command, which uses a more sophisticated dependency resolution technique.