please refer to the following WP.com Support Documentation Page Visibility — Support — WordPress.com
Here is the short url http://wp.me/2nREg to your websites home page this method works for post and pages as well you just need to have the page or post link loaded in your browser url bar first, then hover over your site name on the left side of your grey admin bar then you will see a short url for such post or page...
screenshot reference http://i.imgur.com/gvv7W.png
Please also leave a descriptive title when creating forum threads this will aid the volunteers with answering your question(s)
Also please considered searching the forums by using the search fieldd at the top of the forum page as well search the support documentations before creating a new thread this helps with cutting down on redundant threads thanks in advance for your cooperation.