To connect 2 or more monitors to a computer your graphic hardware has to support it. In most cases you got 2 connectors on one graphic card.
It is possible that 2 different connectors are located at your graphiccard. So you need 2 different monitors, or a converter.
At last, you have to setup your graphics driver in you operating system to use 2 monitors. There are several modes you can use 2 monitors with:
- clone (displays on both the same thing)
- large desktop (makes your desktop larger)