Not trying to be an ass here, but it is called a cable. I am curious, though, did your computer come with a s/pdif? They are not generally standard equipment. Also, the cable you use for connecting your multitrack to your computer depends on what type of s/pdif you have. Is it optical (sort of a rectangular hole with a light shining when the jack has a signal coming from it) or coaxial (actually RCA type)? Does your multitrack s/pdif match your computer's? Otherwise you will need to also get an adapter to match s/pdif connectors. Hope that answers your question more than raise more questions. And don't be offended if you already know all about s/pdif terminology, but you said you were a novice.
Peace, Jim