I would like to know how to create a user profile (registered user block) similar to the one on this site. I am using Drupal 7 and the Zen theme.
In Drupal 7, users accounts are fieldable entities like nodes. From Administration » Configuration » People » Account settings, you can add fields and configure their display on the user page (ie. /user/$uid).
For a more complex setting with multiple profile types and separation of accounts (ie. user) and profiles, you can use the Profile2 module.
You can then use Views to easily crate blocks and pages to list users and information from their profiles.
If you want more control over the layout you can also do a template override on the user-profile.tpl.php. Just copy it from /modules/users directory into your current theme directory and make changes there.
In Views you can create a block views and place it where you want, but if you wanna personalize it you need to use the Context module.
Also you can go "yourpage.com"/admin/config/people/accounts/fields and create some custom field for your profile and then go to "yourpage.com"/admin/config/people/accounts/display to customise how it looks.
But if you wanna override the drupal /user/ page you need ctool and the page manager that is a componet of ctool, there is a video tutorial here and there is a plugin module called Contextual Administration and the video tutorial is about how to use it (http://www.youtube.com/watch?v=R5gpUfAXrAg) his blog is (https://plus.google.com/u/0/107801555171748743621/posts)