The process of adding a directory to CVS is similar:

# mkdir foo
# cvs add foo
Directory /home/cvsroot/mycode/foo added to the repository   

Unlike adding a file, when you add a directory it appears on the repository immediately; a cvs commit isn't required. Once you add a local directory to cvs, you'll notice that a "CVS" directory will be created inside it to serve as a container for cvs accounting data. Thus, you can easily tell if a particular directory has been added to cvs by looking inside it for a "CVS" directory.