You can disable Visual Mode entirely by visiting the "Editing" tab in your preferences, opening the "Preferred editor" dropdown, then selecting "Source editor". This mode may be preferred for editors who edit complex templates frequently.
Editing tools
The classic editor layout
Edit Area
This is the main content area where you can add text, media and make adjustments to the layout of the page.
Toolbar
The toolbar allows you to format text, making it different sizes and styles. You can expand and condense the toolbar to view more or less tools.
Feature Modules
The right pane includes modules that allow you to add features and media such as photos, slideshow, videos and tables. You can also access templates to use on the page and add categories. The preview and publish buttons are found at the top of this area.
Quick tips
To see how your page will appear once it's published, click on one of the preview buttons (Mobile or Desktop) - this will pop up a box containing a preview of how the page will appear on that device type. The preview will also let you switch between types using a dropdown at the top of the box.
If you like your preview, hit publish and your edits will be pushed live.
If you don't like your preview, you can keep editing until it appears as you would like it to.
To let others know what you changed, fill in a summary above the publish button.
Notes
Due to some issues with Internet Explorer 11, the classic editor's visual mode is not currently available when using this browser.
See here for an explanation of FANDOM's editor user preferences.