How can My users register, it only has a login link.
If you have "Allow registrations" set in your configuration panel, you will see a register link on your system menu. If you don't, check your theme. You can try the classic theme to make sure you see it. Then you can add that link to your current theme or add it to the login form. This has been discussed before, I believe.
Allow new user registrations (http://coppermine-gallery.net/demo/cpg14x/docs/index.htm#admin_allow_registration)