understanding Software Components (SCs)

I'm slowly getting a handle on configuring and putting a JDI into practice. What I don't understand is the concept of assigning SC's to a track. I have created a development track, and can import it into NWDS. We have 2 basic J2EE Web Dynpro projects going on that are going to enhance functionality of an SAP SD module process. How do I know which SC to assign, or how to go about finding it in the list of 3000+ of them?