Friendly URLs in WebSphere Portal 6.1 is disabled by default. In order to enable it please add friendly.enabled to true in Resources -> Resource Environment -> Resource Environment Providers > WP ConfigService from WebSphere App Server admin console. You can access the admin console by using the URL http://localhost:10027/admin.
Now you can create and confirm friendly URL for a page let us say My Page which is located inside Content Root.
Another thing worth to note is that a path must reflect pages hierarchy. The above example works only when My Page is placed below Content Root. In order to place the page under Home, a friendly URL for Home label must be also created (for example: home) and then the path to My Page would be: