Hi Alfredopacino,
For the login in the site, we use JA Login module:
http://www.joomlart.com/forums/downloads.php?do=cat&id=448
To have the login module like this site, follow the steps below:
#1: define a position in header block (position "head-login"
Open header.php file (templates/t3_bs3_blank/tpls/blocks) then add the code to define "head-login" position.
<?php if ($this->countModules('head-login')) : ?>
<!-- HEAD LOGIN -->
<div class="span2<?php $this->_c('head-login')?>">
<div class="head-login">
<jdoc:include type="modules" name="<?php $this->_p('head-login') ?>" style="raw" />
</div>
</div>
<!-- //HEAD LOGIN -->
<?php endif ?>
#2: install JA Login module, enable it, assign to all pages and assign to position "head-login"
#3: you may need to add some style to make it look good on your site.
Hope it will be helpful for you
Regards