I guess I should click File and then abc. However, when I click File, the Info screen appears and abc does not.
It's not "File" that is selected in my screen shot, it is "Home" (the tab to the right of "File"). If you look at the screen shot carefully you should see this.
(The "File" tab is always coloured differently from the others.)
This is what I do in Word 2013 to make text struck through:
1. Having typed some text which I want to be struck through, highlight that text.
2. On the "Ribbon" at the top, click the "Home" tab (the second tab reading from left to right, the one immediately to the right of "File")
3. You will see in the Ribbon a section named "Font". In there you can see a font chooser, size chooser, and styles including Bold, Italic, Underline, Strikethrough, Subscript, Superscript, Outline, etc. The styles are shown by little examples. Click on the one(s) you want to apply to your text. Click again to unapply. When a style is selected it becomes coloured. In my screen shot you can see that the strikethrough style is shown by the letters 'abc' with a line through them.