Inserting the logged in user name automatically in the "Name" in the comment form on the blog?

I found these codes in _x5engine.php_ but I can not make it work:

/**
* Get an array of data about the logged user
*
* @method whoIsLogged
*
* @return {mixed} An array containing the data of the current logged user or false if no user is logged.
*/
function whoIsLogged()
{
global $imSettings;
if (isset($_SESSION[$this->session_uname]) && $_SESSION[$this->session_uname] != "" && isset($_SESSION[$this->session_uname])) {
$uname = $this->_decode($_SESSION[$this->session_uname], $this->salt);
return array(
"username" => $uname,
"uid" => $this->_decode($_SESSION[$this->session_uid], $this->salt),
"realname" => $this->_decode($_SESSION[$this->session_real_name], $this->salt),
"groups" => $_SESSION[$this->session_gids]
);
}
return false;
}

.

.

.

/*
|-------------------------------------------
| Show the form
|-------------------------------------------
*/

if (isset($_GET[$this->id . 'success'])) {
echo "<div class=\"alert alert-green\">" . l10n('blog_send_confirmation') . "</div>";
} else if (isset($_GET[$this->id . 'error'])) {
echo "<div class=\"alert alert-red\">" . l10n('blog_send_error') . "</div>";
}

echo "<div class=\"topic-form\">
<form id=\"" . $id ."\" action=\"" . $this->posturl . "\" method=\"post\" onsubmit=\"return x5engine.imForm.validate(this, {type: 'tip', showAll: true})\">
<input type=\"hidden\" name=\"post_id\" value=\"" . $this->id . "\"/>
<div class=\"topic-form-row\">
<label for=\"" . $id . "-name\" style=\"float: left; width: 100px;\">" . l10n('blog_name') . "*</label> <input type=\"text\" id=\"" . $id . "-name\" name=\"name\" class=\"imfield mandatory\" value=\" HERE COMES THE NAME "realname" DO LOGGED USER \" />
</div>
<div class=\"topic-form-row\">
<label for=\"" . $id . "-email\" style=\"float: left; width: 100px;\">" . l10n('blog_email') . "*</label> <input type=\"text\" id=\"" . $id . "-email\" name=\"email\" class=\"imfield mandatory valEmail\"/>
</div>
<div class=\"topic-form-row\">
<label for=\"" . $id . "-url\" style=\"float: left; width: 100px;\">" . l10n('blog_website') . "</label> <input type=\"text\" id=\"" . $id . "-url\" name=\"url\" />
</div>";

EXCUSE ME WRITING BECAUSE I DO NOT SPEAK ENGLISH