Writing IF conditional statements in SharePoint calculated column fields are not like you would write using a traditional programming language structure. In an earlier blog post (Fun with SharePoint Calculated Columns), I showed how to take a real-world example and create a complex nested IF formula.
Webucator has taken that blog post (also cross posted on SharePoint-Community.net) and created a step-by-step video tutorial of the process, which in my opinion, explains how to create complex SharePoint calculated column nested IF statements much better than I did. Check it out below! And check out all the great SharePoint classes that they offer.