There are multiple sequences of keystrokes to try in web pages, HTML, and Microsoft Word. Each method appear to work in the systems we've tried, but if one set doesn't work, try the others. NOTE: For the numbers use the numeric keypad, not the upper keyboard numbers. Use the [Alt] key on your keyboard.
(1) Hold down the [Alt] key and on the numeric keypad press the digits "0", "1", "6" and "7" in that order, then release the [Alt] key.
Alt 0167 = §
(2) Hold down the [Alt] key and on the numeric keypad press the digits "2" and "1" in that order, then release the [Alt] key.
Alt 21 = §
(3) Hold down the [Alt] key and on the numeric keypad press the digits "7" "8" and "9" in that order, then release the [Alt] key.
Alt 789 = §
(4) In a Word document you should be able to select the insert tab and then click the symbol tab.
(5) Although not an ideal solution, you could also try copying and pasting the symbol § from this page into your document and then adjusting the size to fit the rest of your font text.
(6) "On a Macbook air running OSX High Sierra... Option/Alt 6 is the keyboard pair that gets you this §" (user suggestion) -- "confirmed that on MacOS X with US keyboard, the key combo is alt-6" (user suggestion)
If none of these methods work, consult with a technical expert in your country or region familiar with the operating system, browser, hardware, software, keyboard, and fonts you are using. We have no capability for inspecting your specific computer setup.