Okay, well your main is connected through DVI and secondary through VGA, as long as both of these ports are on your video card then you should be able to activate them by right clicking on your desktop background and selecting screen resolution, you should see 2 monitors in the graphic, if not then your computer does not see the second monitor, if it does but number 2 is grayed out click on it and select extend desktop check-box.
If this doesn't work there may be some driver issues which means you just reinstall the driver from the disk that came with your card or from online support.