The trunkurl would be something like svn:://localhost/myrepo
or if you're using apache http://localhost/svn/myrepo
.
and working directory is where you want to check out the repository to on your local disk.
Have you created a repository using svnadmin create <reponame>
? You need to do that first. Bring up a command prompt and type 'where svnadmin'. If you don't have it go here http://sourceforge.net/projects/win32svn/