The editor is where your website is actually built, once you have chosen a template to begin working on you will be directed to the Website Builder editor. There is no software required to use the editor, it runs right within your web browser.
The bars at the top and side are your controls and tools, these are permanently displayed in the editor. The majority of the page displays one of your website pages, to change which page is being viewed here click the drop down menu on the top bar and click a different page. The top bar also has a view switcher, as standard it will be set to view your website in desktop mode, by clicking the mobile icon this will change to the mobile justified view of your website. On the right hand side of the top bar there are options to preview, save and publish your website.
The sidebar contains the tools you will use to manage your pages, add content to your website and change the look and design.
Clicking on any element on your website will select it. It is likely you will be familiar with this process from other software, any element you click on will show a containing box - this enables you to drag the element where you wish on the page, resize it perhaps or, most likely, access a range of editing tools. Each element selected will bring up a tools palette, most likely on the right side of the screen. The tools palette is where all the settings and controls, for the selected element only, are controlled.
Double-clicking on a piece of text enables you to edit it, a cursor will appear along with a palette of text tools to control the font size, alignment, colour, etc.
The Pages tab on the sidebar is where website pages are controlled. From this menu you can add new pages, delete existing pages, rename a page and change the order of pages. As well as ordering, pages can be dragged with an indent under another page to become a child page of it. Clicking Manage Pages on the Pages menu opens up some more advanced page controls. You can define the URL of each page, choose whether you want the page to be hidden in desktop or mobile view as well as controlling page specific meta data.
Clicking the Add tab on the sidebar reveals a host of different features you can add to a Website Builder website. This includes the ability to add images, galleries of images, social links, Google Maps, icons & shapes, buttons, embed HTML, embed videos and much more.
The Design tab on the sidebar is where text styles are controlled, here you can define how you want headings, sub-titles and paragraph text to look. You can also define the key colours used across your website and the page background.
Remember to save your work regularly by hitting the save button on the top bar. Once you are done editing and want your website live on the web, click Publish, again, up on the top bar. The first time you hit publish, you need to define a name for your website. If you are using Website Builder for free this name will make up the URL of your website (i.e. http://my-website-name.myfreesites.net). If you are using Website Builder as a paid user with a domain name, what you call your website here isn't particularly important as your domain name is what your visitors will be typing in or seeing if they get to your site from a link elsewhere.
There are a number of other articles in this help centre on specific features in the editor, this is a brief overview to get you started.