Bring the machine up to date
From Synaptic Package Manager, press the Reload button. This will update the package lists to the latest packages. Press the Mark All Upgrades button and all of the newer packages will be "marked".
You may want to review the list of proposed updates to disable installation of packages you may not want or need- e.g. Open Office, etc. If asked to restart, follow the directions indicated.
Press the Apply button and everything installed will be updated to the latest version. If your system needs to be restarted, you will receive a popup indicating so.