Welcome to Apple Support Communities
There are some apps you can use to do it:
1. Microsoft Word. Word is available for OS X, and you can use it if you are familiar with Microsoft Word > http://www.microsoft.com/mac
2. Pages. It's Apple's Word version and can be get in the App Store. If you need basic features, it will work correctly.
3. LibreOffice. It's free, so you may want to try it first before the other applications > http://www.libreoffice.org