There is no pre-existing shortcut for inserting the section (§) symbol, but you can create a custom shortcut by following these steps:
1. From the Word toolbar, select Insert > Symbol > More Symbols.
2. When the pop-up appears, select the Special Characters tab. Click on the Section symbol to highlight it, then click the Shortcut Key button.
3. When the Shortcut Key pop-up opens, the cursor will appear in the Press new shortcut key box. Press and hold the Ctrl key and then also press the key you want to assign as the shortcut key. When you are through, click assign.
To insert the Section (§) symbol: Option + 6