No need to get a paper copy of The Decisions, there are excellent apps available for both, iPhone and Android that describe The Decisions. If you don't have a smartphone, check the R&A website
here (I like the R&A website better than the USGA site for this purpose but you may think otherwise).
As for the sketched situation, you're talking about a drop area. That means the course must have a local rule that explains how to use it. Maybe it says you
must use it, maybe it says you
may use it.
Anyhow, read the rules carefully, they will make sense (part III of the rulebook). Be aware of the differences between "you may", "you must" or "you should". Make sure you read and understand the definitions (part II of the rulebook).
Ow,check out the website from Barry Rhodes (http://www.barryrhodes.com/) and if you want more, do subscribe to his weekly newsletter/e-mail. You'll learn a bunch from that!