convert to CI

I try clicking the navigation but it does not work out well.

views/index.php

PHP Code:

<div id="sidebar"> 
        <h1 id="logo"><a href="index.php">Free Admin</a></h1>  
        <a href="#" class="visible-phone"><i class="icon icon-home"></i> Dashboard</a>
        <ul>
            <li class="active"><a href="index.php"><i class="icon icon-home"></i> <span>Administrator</span></a></li>
            <li class="submenu">
                <a href="#"><i class="icon icon-th-list"></i> <span>Categories</span> <span class="label">2</span></a>
                <ul>
                    <li><a href="pcategories.php">Parent categories</a></li>
                    <li><a href="scategories.php">Sub Categories</a></li>
                </ul>
            </li>
            <li><a href="<?php echo site_url('pages'); ?>"><i class="icon icon-tint"></i> <span>Pages</span></a></li>
            <li><a href="#"><i class="icon icon-pencil"></i> <span>Slideshow</span></a></li>
            <li><a href="#"><i class="icon icon-th"></i> <span>Content</span></a></li>
            <li><a href="#"><i class="icon icon-th-list"></i> <span>Galleries</span></a></li>
            <li><a href="newsletter.php"><i class="icon icon-th-list"></i><span>Newsletters</span></a></li>            
            <li class="submenu">
                <a href="#"><i class="icon icon-file"></i> <span>Administrators</span><span class="label">2</span></a>
                <ul>
                    <li><a href="#">User</a></li>
                    <li><a href="#">Role</a></li>                    
                </ul>
            </li>
            <li><a href="#"><i class="icon icon-th-list"></i> <span>Settings</span></a></li>
            <li>
                <a href="#"><i class="icon icon-inbox"></i> <span>Logout</span></a>
            </li>
        </ul>
    </div> 


controllers/Welcome.php

PHP Code:

public function pages()
    {
                
        $this->load->view('pages');
        
    } 


" If I looks more intelligence please increase my reputation."