you have several options:
1 - use the existing VGA and HDMI connections directly as long as the monitors have matching inputs
2 - buy a cheap card, go into BIOS, make sure IGP is enabled, and run both onboard plus card
3 - buy a cheap card, ignore BIOS and onboard, and run both monitors from the card (typically cheap cards do VGA, HDMI, and DVI, and the dvi port can be converted to VGA)