Most software will require that you know your administrator password to install correctly. You are responsible for your own administrator password. When your computer was initially set up (assuming it was set up at EIT), an administrator password was set and included with the paperwork you received with the computer.
Software installation on current versions of Windows with the addition of User Access Control (UAC) is simpler than in previous versions of Windows. Instead of requiring you to log out of your current desktop and log in as administrator, you can launch the installation of your new application while remaining logged in as yourself. When the installation requests your administrative credentials, UAC will prompt you for administrator name and password. Once you've entered the correct information, the program will finish installing.
Macintosh software installs will also generally require that you know you're administrator password. Again if the computer was set up at EIT, you should have received your administrator password as part of your paperwork. When installing new software or upgrading, run the installer and provide your administrator password when requested.
Applications off the internet
One of the ways that viruses and other malware are spread is through applications downloaded off the internet. Only download trusted applications from trusted sites.