Here is simple tutorial that explains how to protect your word documents with password.
1. Open your word documents and go to Tools => Options => Security

2. Under Options , select Security tab and type password to modify and password to open , click on OK

 3. After this your file will be protected with password. When you try to open word file you’ll need to type password, also when you’re try to modify content. This double password protection can prevent an attacker to access and change data from your word document.