OT- Need help with older laptop

[Combat Wombat]

Alright I have this great little IBM laptop "PS/2 Model L40 SX" is what it is called. It is running Windows 3.11. I cannot for the life of me figure out how to get the display to switch from the laptop screen to the CRT I have hooked up to it. Can anyone help me?

[Combat Wombat]

It has a 386sx-16 CPU, 2 meg of memory and an 80 meg hard drive as well as a monchrome VGA screen. Power management was a standard feature as was the 1.44 floppy drive which is a standard form factor that was used in the later black Thinkpad models. The L40SX even has temperature and humidity sensors that will prevent operation until the machine can acclimate to room temperature.

http://www.walshcomptech.com/ps2/images/l40sx.jpg