The using keyword is both a directive (this topic) and a statement.
For the using statement (i.e. to encapsulate the scope of an IDisposable object, ensuring that outside of that scope the object becomes cleanly disposed) please see Using Statement.
echo %cd% - displays the current path of the directory
cd "C:\path\to\some\directory" -changes the path of the directory
cd "%variable_containing_directory_path%" - also changes the path of the directory
cd /d E: - change to E: drive from a different drive