To view two parts of the same document, click on the View tab on the Word Ribbon and locate the section named Window and the click on the Split button.
Word will immediately place a grey line on the screen that you can move up and down with your mouse. This line is simply where you want the split to be on the screen. Just click the left mouse button where you want the initial split. You can move it anywhere to make one or the other split screens the size you want.
Notice that you now have two views of the same document. You can scroll each one independently of the other and see two places in your word document at the same time.
Each view of the document is treated like two separate documents even though you are viewing the same one. You can zoom, scroll, and even change the type of view (print, draft, outline, etc.) for each view individually. Any changes you make into one view will be made to the other view as well. You can edit the text in either view by simply clicking on it and typing.