How to create a simple "Hello World" module in Magento?

How can the following be accomplish in Magento?

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  Display a "Hello World" message using a controller/view/model approach. So, if I went to http://mysite.com/myController it would show the string 'Hello World'. Being able to show this string within the template of my website (for example, the header, footer, etc.) will be a bonus.
  

  
  

Can someone recommend some Magento tutorials?

I am trying to learn Magento, where can I find some video tutorials?

Accessing custom options of an order in Magento via PHP

I'm loading an order like this:

$order = Mage::getModel('sales/order')->load(2886);

$items = $order->getAllItems();

Why is the Relation Between a Configurable Product and a Simple Product Stored Twice?

Deep dive on the Magento internals here, not looking for a solution to a concrete problem, just trying to understand some implementation details.

Format of Exported Reflection Class in PHP?

Every Object in PHP's Reflection hierarchy has a static export method. You can can use this to get a string representation of a class. Code something like this

photo upload field error in magento

Below i have added the code to upload photo. Well i have added photo upload in edit.phtml page only but in register.phtml magento showing error. Can anyone fix it ?

How to check an already existing record in Magento?

I am trying to perform an SQL query kind of thing where I need to check if my database table contains a particular record or not. If it does, do nothing else add the record which isn't present.

Magento Best Way to Call Modalbox After Item is Added to Cart

I'm looking for a way to call a Modalbox (http://okonet.ru/projects/modalbox/index.html) after a customer has added an item to a cart...