I want to connect 2 monitors to my laptop; what external device do I need to by and from where?

Attach both monitors to the computer. A computer that enables dual monitors has two connectors on the video card. Locate the video card on the machine and attach the cables from the monitors.
Click the "2" monitor in the automatic popup window that displays. This window is shown as soon as a second monitor is attached. Once you've click the "2" monitor icon, check the box labeled "Extend the desktop onto this monitor."
Use the mouse cursor to drag the monitor icons into the same position and display layout as your monitors. This helps you set and arrange the display of each monitor.
Click the "Apply" button. Once you have selected the configuration, Windows takes a few seconds to change the display. Your screen may go black during this time.
Click the "Yes" button at the confirmation screen. Windows changes the configuration and gives you a preview of the screen. If the settings do not display correctly, you can choose "No" to void the new configurations.

which laptop do you have? you need a docking station or port replicator as many have the capabilities to support 2 external monitors