Upgradging/adding Graphics card to have 2 monitors for Dell Vostro 230 slim tower

Hi, I have Dell Vostro 230 Slim Tower with built in graphics as default i believe, I want to purchase and add separate Graphic card for multi-screen option to have 2 monitors working with pc.

COULD ANYONE PLEASE ADVISE WHAT KIND OF CARD SHOULD I BUY IN TERMS OF COMPATIBILITY AND MULTI-SCREEN FUNCTIONALITY? THANKS