When buying a new motherboard it always contain a DVD with all their drivers, not the uppdated ones that you in most cases need to uppdate to make those work better, but everything you need to make it installed regardless how good or bad they work. If you did´nt built your PC by yourself and a local PC store (not the big companies that exist everywhere) built it for you, you only have do walk back to them and ask for this DVD that somehow did´nt got home to you with your new PC.
They can also download the newest uppdates and burn them on a CD/DVD for you for a small fee. Ask if they can make it to run the setup program automaticly when you push in the DVD, but if they cant its just to open the explorer (not Internet Explorer) and click on the blue icon named "setup.exe" in one of the DVDs maps. Its usually lays in the chipset map. If you buyed a brand PC on a big market store you can ask them to take contact with the motherboard manufactor and send the DVD to you, but I recomend you to walk in to a local store and make them burn it for you, and as a bonus you as i said will get the latest versions. DONT take your computer with you and let a PC store open it, screw the components apart and tell you what you got inside, that costs only alot of wasted money.
As PhillFrisbie said look up what motherboard you have. If know which brand it is but is unsure what model you have, you can google the name or visit the brand manufactors website and look on pictures until you find one that looks like the one you have. Those websites often hawe their own hardware scaner you can download and make it search and tell you exactly what you have inside the case.