Installing MySQL on OS X can be as easy or as complex as you want it to be. On the complex side, since OS X is UNIX, you could install from source and build your own package. Or your could use the Homebrew package manager to install completely from the command line.
The easiest way to get MySQL installed on OS X is to use the packages built by MySQL. The packages are offered up in tarball or in DMG. Getting the DMG is going to give you the most ‘Mac’ like install. For the purpose of simplicity, this is the method we will use in this example.