When you add new materials using the Add Materials button at the top of your course Materials page, the item will automatically be added to the bottom of your Materials page, below the other previously created content.
It is possible to drag and drop to the desired point on the page or into the folder you plan to house the item in.
However, if you would like to add a material item inline somewhere else on the page, hover your mouse over one of the gray lines between folders or items on the page.
When you hover over the line, a green + sign will appear. Click on the dotted green line and select a material type from the dropdown menu to add an item to a specific spot on the page.
Or, directly into a folder: