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

    class MageSf_OrderCustom_Adminhtml_UploadController extends Mage_Adminhtml_Controller_Action {	
    	public function uploadAction() {
            if ($data = $this->getRequest()->getPost()) {
                if (isset($_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']);
                        $uploadeddocname = $uploader->getUploadedDocname();
    
                    } catch (Exception $e) {
                        
                    }
                    $data['docname'] = $uploader->getUploadedDocname();
                }
            }
            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**

    <form id="doc-form" name="doc-form" method="post" action="<?php echo Mage::helper('adminhtml')->getUrl('adminhtml/upload/upload', array('_secure' => true)); ?>" 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>