In the YaST control center, click on Hardware. On the right side of the screen, click on Sound. The screen that comes up will tell you if your sound card is configured. If it isn't, click on Add to add and configure the card.
Also, in a terminal, if you have hwinfo installed, run '/usr/sbin/hwinfo --sound'. The output should identify your sound card, the driver needed, whether or not the driver is active, and the command to run to activate the driver.