Magento get post data from url

$this->getRequest()->getParam(key);
$arrParams = Mage::app()->getRequest()->getParams();
print_r($arrParams);

Magento Get Admin Url with key

echo Mage::helper("adminhtml")->getUrl("module_name/action_name/");
Example :

Mage::helper("adminhtml")->getUrl("Ordermanager/adminhtml_ordermanagerbackend/");
Ordermanager:=module_name
adminhtml_ordermanagerbackend = my Module action_name

see below in xml
from : app\code\local\Ordermanager\Ordermanager\etc\config.xml

<menu>
 <ordermanager module="ordermanager">
<title>Ordermanager</title>
<sort_order>100</sort_order>
<children>
 <ordermanagerbackend module="ordermanager">
<title>Backend Page Title</title>
<sort_order>0</sort_order>
<action>ordermanager/adminhtml_ordermanagerbackend</action>
 </ordermanagerbackend>
 <ordermanager module="ordermanager">
   <title>Manage Ordermanager</title>
<sort_order>0</sort_order>
<action>ordermanager/adminhtml_ordermanager</action>
 </ordermanager>
</children>
 </ordermanager>
</menu>