In administrator  Menu !!

As far as I know you can't edit the footer area content via the site's admin area. You will have to edit

/views/default/page_elements/footer.php directly.

Of cource ,It can edit.For example:http://s.opentom.com/pg/expages/  ,edit in your site.

If you want to change this sentence to something else change it in the

Powered by Elgg, the leading open source social networking platform"

/views/default/page_elements/footer.php  as iionly said

the powered by elgg icon can be changed by replacing it with your own in your theme _graphics folder

or If you want to add more links to the external pages like

| About | Terms | Privacy | FAQ | Advertise   .... etc then follow these instructions

Backup the files before editing

This is how to add the FAQ -->

1) Open this directory – \mod\externalpages\languages\en.php\ and seek the following line-
‘expages:privacy’ => “Privacy”,
Add the following code after this line-
‘expages:faq’ => “Faq”,

2) Open this directory – \mod\externalpages\views\default\expages\footer_menu.php\ and seek the following line-
<a href=”<?php echo $vars['url']; ?>pg/expages/read/Privacy/”><?php echo elgg_echo(‘expages:privacy’); ?></a> |
Add the following code after this line-
<a href=”<?php echo $vars['url']; ?>pg/expages/read/Faq/”><?php echo elgg_echo(‘expages:faq’); ?></a> |

3) Open this directory – \mod\externalpages\views\default\expages\menu.php\ and seek the following line-
<li <?php if($type == ‘privacy’) echo “class = ‘selected’”; ?>><a href=”<?php echo $url; ?>privacy”><?php echo elgg_echo(‘expages:privacy’); ?></a></li>
Add the following code after this line-
<li <?php if($type == ‘faq’) echo “class = ‘selected’”; ?>><a href=”<?php echo $url; ?>faq”><?php echo elgg_echo(‘expages:faq’); ?></a></li>

 4) Open this directory – \mod\externalpages\views\default\expages\forms\edit.php\ and seek the following line-
else if($type == ‘privacy’) {
$external_page_title = elgg_echo(‘expages:privacy’);
}
Add the following code after this line-
else if($type == ‘faq’) {
$external_page_title = elgg_echo(‘expages:faq’);
}

5) Save all files and upload the modified plugin.

6) Then, run the upgrade.php script by hitting http://SITEURL/upgrade.php in address-bar.

HaPPy ElGGInG :)

Do GooD :)