How to add an additional monitor

Step 2: On your desktop right click and select screen resolution

Step 3: Select the 2nd Display monitor

Step 4: Select extend display and click Apply

Step 5: Adjust screen position

Depending on where your screen is positioned (Left or right) of your main monitor, you may want to move it. If your 2nd screen is positioned on the left of your main monitor you can simply click and drag the 2nd screen to the left hand side and click apply.
 

Step 6: Main your 2nd screen your main monitor

Select the 2nd screen and tick the check box as follows: