How to get post data variables after submition a form in magento

You can get all variables using $this->getRequest()->getParams();. This will return all variables. For any particular name like id you can use $this->getRequest()->getParam('id'); without the "s". Hope this will help.

You can read the values with

$this->getRequest()->getParam('field_name');

The code above will get you values from GET and POST. But if you want to check if something was sent specifically through POST you can get it like this.

$this->getRequest()->getPost('field_name');

You can even specify a default value.

$somevar = $this->getRequest()->getParam('some_var', 7);

this means that if $_POST['some_var'] is not set, the variable $somevar will have the value 7.