Content includes all the items that are a part of your course, and D2L allows you to place items in your course in a variety of ways.
After creating a module, notice the options New and Add Existing Activities.
While adding content items is standard, many of your items may be files. D2L files should be thought of a the webpages that you're creating for your course. If, for example, you wanted to have a project introduction page, you would most likely need text, links, images, or videos all in one place. That place (or webpage) is called a File.
Creating a File & Inserting Stuff
D2L has some language that is helpful to know as you get started.
This example, from a module on how to use Microsoft Word, shows a fully-developed file that includes text, images, links, and videos. Notice how the "Create a File" option allows you to better organize content. Once you create a file, it can become one of the items in your module. The D2L text editor is easy to use and requires no knowledge of coding.
To create a file:
In addition to text editing, you may also use the Insert Stuff option for adding content to a File: