Summarize this article:

The ribbon is the horizontal menu between your document title and the document itself. You'll see this on the far right, in the Symbols group. A box will appear at the position of your text cursor. You can start typing immediately to start your equation or continue to the next step for more options. When you clicked the Equations icon, the ribbon menu changed to display a large array of new options. Browse through them to find what you need, then type to complete the equation. Here's a step by step example:  Click the Script icon to open a drop-down menu. Hover over each button and a tooltip will appear telling you what it is. Select the basic subscript option, and two squares will appear in your equation, one below the other: □□  Click the first square and type in the value you'd like to display: 5□  Click the second square and type in the subscript value: 53 If you do not need any special formatting, just continue typing to extend the equation. Word will automatically insert spaces and italicize variables. Select the entire equation text box, and you'll see a tab with an arrow on the right-hand side. Click this arrow to reveal a list of visual options, including whether to center, left-justify, or right-justify the equation. You can also highlight the text in the equation and alter the font size and style as usual. If you have Word 2016, you can create an "equation" by drawing it with a mouse or touchscreen tool. Select Ink Equation from the drop-down Equations menu to get started.

Summary:
Select the Insert tab on the ribbon. Find the Equation icon (π). Click the icon to insert an equation. Insert special formatting. Continue typing to complete the equation. Move the equation on the page. Write equations by hand (2016 only).