One of the most important things you can do to further your understanding of your computer and its file system is to turn on file extensions. A file extension is the suffix to the file name, (i.e., .JPG, .GIF, .EXE), and is the key to knowing what each file is or does in the general sense. It is how the operating system determines what to do with the file when you click it. You, too, need to know and become familiar with the various file extension types so you can make informed decisions about the disposition of your files. Thousands and thousands of people across the world contracted the "I Love You" virus because they were ignorant of what the .VBS file extension meant and was capable of doing. Ignorance is bliss they say, but it can also get you into serious trouble. When working with stationery, it will be important to become familiar with them.
On the taskbar, click on START|SETTINGS|FOLDER OPTIONS, then click on the VIEW tab of the resulting window. The following window will appear:

To turn on file extensions, check the SHOW ALL FILES radio button, and insure the HIDE FILE EXTENSIONS FOR KNOWN FILE TYPES box is unchecked. When complete, click the APPLY and OK buttons and exit the window.
Now, start Windows Explorer in order to view a folder on your hard drive. Regardless of the view setting, notice that each of your files shows its extension. As you get more involved in stationery creation, and your computer in general, you will become familiar with most of the common types.
Congratulations! You have just advanced beyond the elementary level of computing!