Summarize the following:
Do so by opening the red Adobe Reader app with the stylized, white A icon. Then click on File in the menu bar at the top of the screen, click on Open..., select the PDF document you want to type on and click on Open. If you don't already have Adobe Reader, it's available for free from get.adobe.com/reader and can be used with Windows, Mac, and Android operating systems. It's in the upper-left corner of the window. It's a pencil icon in the upper-left part of the window.  A dialog box will open. Click on the small "A" to decrease the text size. Click on the larger "A" to increase the text size.    Your text additions are now saved in the PDF document.

Summary:
Open a PDF document in Adobe Reader. Click on Tools. Click on Fill & Sign. Click on the "Ab" icon in the top-middle of the window. Click on the place in the document where you want to add the text. Adjust the text size. Click on "Type text here" in the dialog box. Type the text you'd like to add to the PDF document. Click on the document outside the dialog box. Click on File in the menu bar and Save in the drop-down menu.