Create a controller file **SfuploadController.php** under **MageSf/OrderCustom/controllers/Adminhtml**

    <?php
    class MageSf_OrderCustom_Adminhtml_SfuploadController extends Mage_Adminhtml_Controller_Action {  
        public function uploadAction() {
    		if (isset($_FILES['docname']['name']) && $_FILES['docname']['name'] != '') {
    			try {
    				$uploader = new Varien_File_Uploader('docname');
    				$uploader->setAllowedExtensions(array('doc','pdf','txt','docx'));
    				$uploader->setAllowCreateFolders(true);
    				$uploader->setAllowRenameFiles(false);
    				$uploader->setFilesDispersion(false);
    				$newDir = "customer_documents";
    
    				$newdirPath = Mage::getBaseDir('media') . DS . "customer_documents";
    
    				if (!file_exists($newdirPath)) {
    					mkdir($newdirPath, 0777);
    				}
    
    				$path = Mage::getBaseDir('media') . DS . $newDir . DS;
    				$resizedPath = Mage::getBaseDir('media') . DS . $newDir;
    				$uploader->save($path, $_FILES['docname']['name']);
    
    			} catch (Exception $e) {
    				
    			}
    		}
            Mage::getSingleton('adminhtml/session')->addError(Mage::helper('brandlogo')->__('Unable to find item to save'));
            $this->_redirectReferer();
        }
    }

Update your **config.xml** and add below code

    <admin> 
    	<routers>
    		 <adminhtml> 
    			 <args> 
    				 <modules> 
    				<MageSf_OrderCustom after="Mage_Adminhtml">MageSf_OrderCustom_Adminhtml</MageSf_OrderCustom> 
    				</modules> 
    			</args>
    	   </adminhtml>
       </routers> 
    </admin>
Update your **ordercustom.phtml** You need to remove all other code from this file.

    <form id="doc-form" name="doc-form" method="post" action="<?php echo Mage::helper('adminhtml')->getUrl('adminhtml/sfupload/upload',array('form_key' => Mage::getSingleton('core/session')->getFormKey())); ?>" enctype="multipart/form-data">
     <label>Upload Document</label>
     <input type="file" title="File" name="docname">
     <button type="submit" title="Save"><span>Upload</span></button>                    
     </form>