In order to play-along-at-home, you'll need to have both Solver and the Analytical Toolpak (Excel add-ins, so called) installed. Sadly, the fallout of Mr. Gates's insistence upon grubbing the odd farthing from Dr. Fulstra by withholding these two add-ins from the default install, lands upon you. You must find your Excel MS Office cd, and do a reinstall / "add" so that these two most valuable elements of Excel are available for engaging in adult analytics. Thank you, Mr. Gates.
Once you've de-lobotomized your copy of Excel, go to "Downloads" and take, "Excel REAL basics," for a test drive of some not-so-basic features of Excel.
If we get feedback to warrant it, we'll put up a detailed section explaining risk, applied probability, Black-Scholes, and real options. Until then, here's an interesting if breezy article from McKinsey on credit derivative risk.