Start by login into your account through Miss Hosting, to the top right you have Log In.

Once logged in with your email and password just click on "Domains" and "My Domains" in the left menu.

On this page, you'll see a summary of your domains, just click on the tool icon on the far right for the domain you want to manage.

Now click on the domain name to the top right and then the "Get Auth Code" text.

Don't forget to unlock your domain if you want to move it!