It may seem like a trivial frill to be able to customize Moodle login page settings and appearances, but believe it or not, this not only shows how flexible Moodle is, but allows a very nice touch for companies or individuals conducting training. Customization shows a level of professionalism, legitimacy and effort, and will put students and subsidiary instructors at peace knowing the powers that be are so on top of things that they can govern the very appearance of the infrastructure at work.
Customizing your login page isn’t difficult, but know that you need to know HTML in order to do it. I’m not here to teach you HTML as that is a long journey, so I recommend copying the HTML text and using a visual editor to modify it, and re-post the HTML into the editor, being sure all values still line up, if you’re not at all proficient with HTML raw editing.
Future versions of Moodle plan to offer a point and click customization for forms and logins, but this is in early alpha testing, so don’t hold your breath for this being available to any useful level for a while yet.
In the mean time, just access the page by going to Users->Authentication->Manage Authentication. You must be an administrator to access this or affect any change.
You may use plugins for Moodle which create preset (and self-customizing) logins, not unlike themes for WordPress or other CMS systems, but you can also scroll down to the instructions field, and modify the HTML, as specified above.
You can add images, set backgrounds, CSS themes, embed video, dynamic text for headlines, and any number of other web-oriented things. Just make sure the login fields are still properly lined up to submit the proper information to the proper place, and that the button still submits with the right parameters.
Don’t tinker with that aspect, and there’s no limit to the ways you can customize Moodle login page aesthetics.