On board networt not working

Question

hi i have hp d330 ut. its not connecting to the net yet the its blinking (the two leds) i added a pci nic card and again not working . its not being seen from device manager either. and there is network adapter its shown has hidden can that be the problen. note: the nic card can be noticed in other pcs and its blinks on the hp d330 ut thou not being seen.need hepl fast please.