found the file system => register.
but i could not understand the code. here is full code
<section class='ipsPad'>
<br>
<h1 class='ipsType_veryLarge ipsType_center ipsType_reset'>{lang='sign_up'}</h1>
<p class='ipsType_large ipsType_center ipsType_light'>{lang="existing_user"} <a href='{url="app=core&module=system&controller=login" seoTemplate="login"}'>{lang="sign_in_short"}</a></p>
<br>
<div data-role='registerForm'>
<div class='ipsColumns ipsColumns_collapseTablet'>
{{if count ( $login->forms( FALSE, TRUE ) ) > 1}}
<div class='ipsColumn ipsColumn_fluid'>
{{endif}}
<div class='ipsBox ipsPad_double {{if count ( $login->forms( FALSE, TRUE ) ) == 1}}cRegister_noSocial ipsPos_center{{endif}}'>
{$form|raw}
</div>
{{if count ( $login->forms( FALSE, TRUE ) ) > 1}}
</div>
<div class='ipsColumn ipsColumn_wide' id='elRegisterSocial'>
<div class='ipsBox ipsPad_double'>
<h2 class='ipsType_sectionHead'>{lang='reg_start_faster'}</h2>
<p class='ipsType_normal ipsType_reset ipsType_light'>{lang='reg_connect'}</p>
<br>
{{foreach $login->forms( FALSE, TRUE ) as $k => $form}}
{{if $k !== '_standard'}}
<div class='ipsType_center'>
{$form|raw}
</div>
{{endif}}
{{endforeach}}
</div>
</div>
{{endif}}
</div>
</div>
</section>