When creating a 2D texture, you can select among one of three mapping methods: create normally (create texture), create as projection, and create as stencil.
When creating a node in the Node Editor using the Tab key, as you enter the name of your desired 2D texture type, three variations of the texture appear (Projection, Stencil, Texture), allowing you to select among the three mapping methods. See Create a node for more information on how to create a node using the Tab key.
Creating a file node using drag and drop
You can 
an image file from the Visor to the Node Editor, or 
an image file from Windows Explorer to the Node Editor to create a file node and automatically assign to it your image file.