Your sites both are good..
in order to have blog, you must make subdomain blog.yourdomain.com or just add directory www.yourdomain.com/blog
after that use your hosting service to install blog script
You can also place one of your blogs in an iframe on the page so that you can update it only once and it updates on both sites. If you are using "Blogger" for example, this would make it easier to keep it updated.