If you go to click here and click the link at the right "Link for the Old Page" it takes you to listings on an 'ftp' server. You need to find the listing that relates to the date and operating system of your PC.
Drivers will normally be either a .ZIP file or a self-extracting .EXE file. Extract the contents into a folder where you know you can find them again. Go into Device Manager and double click your sound card (probably with a "question" or "exclamation" mark against it) to open its Properties sheet. In the Drivers tab, click the option to update drivers. Choose to install from a specific location and 'browse' to the folder where you extracted the files. Windows will probably look for an .INF file and then install the sound drivers.