`svnadmin create` on an existing set of source files

Hi Everyone,

I have my source files in /var/test-svn. The test-svn directory has
*.h and *.c files. I am trying to create a repo from them.

As root, I perform the following:

    # cd /var
    # svnadmin create --fs-type fsfs test-svn
    svnadmin: E200011: Repository creation failed
    svnadmin: E200011: Could not create top-level directory
    svnadmin: E200011: 'test-svn' exists and is non-empty

I think I am missing something from my reading, like at
<https://svnbook.red-bean.com/en/1.7/svn.ref.svnadmin.html#svn.ref.svnadmin.c>
and <https://svnbook.red-bean.com/en/1.7/svn.ref.svnadmin.c.create.html>.
My apologies for my rusty knowledge of subversion. I've been stuck in
the git world for far too long.

So the question is, how do I create a repo from an existing set of
project files?

Jeff