Create a custom page in Magento

<!---- First Create One Phtml File  -----> 
 ==> Go to app/design/forntend/default/base/tamplet/catalog/product ==> Here Copy any phtml file, ==> Paste that copied file, ==> Change the name with your Name ==> Example ::=> categoryid.phtml

 <!---- Second Create One Php File  ----->
 ==> Go to app/code/core/mage/catalog/block/product ==> Here Copy PHP file Which name is as your phtml file which you select and copy-paste, ==> Paste that PHP copied file, ==> Change the name with Same name of PHtml file and Must "First character be a Capital" ==> Example ::=> Categoryid.php

 
 <!---- Third Add this code in Product controller File  ----->
 ==> Go to app/code/core/mage/catalog/controller ==> Put belove code in this file 
  public function "Here your phtml file name in small letter"Action()  { 
   $this->loadLayout();
          $this->renderLayout();  }
 ==> Example ::=>
  public function categoryidAction()  { 
   $this->loadLayout();
          $this->renderLayout();  }
 
 <!---- Fourth Add this code in Catalog.xml File  ----->
 ==> Go to app/design/forntend/default/base/layout/catalog.xml ==> Put belove code in this file
  <catalog_product_Your Phtml file Name>
    <reference name="content">    <block name="Your Phtml file Name" template="catalog/product/Your Phtml file Name.phtml" type="catalog/product_Your Phtml file Name" as="Your Phtml file Name"/>
    </reference>  </catalog_product_Your Phtml file Name>
 ==> Example ::=>
  <catalog_product_categoryid>
    <reference name="content">    <block name="category" template="catalog/product/categoryid.phtml" type="catalog/product_categoryid" as="categoryid"/>
    </reference>  </catalog_product_categoryid>

And at Last Please Clean Cache from Admin

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