As we know that we can simply embed search in theme which is mentioned in http://www.liferaysolution.com/2011/12/embed-search-and-web-content-search.html
But If you want to embed search in theme and want to redirect on specific fix community page then you may need some modification and can use below code in you theme .vm file :
#set ($layoutService = $serviceLocator.findService('com.liferay.portal.service.LayoutLocalService') )
#set ($selectedPageGroup = $groupLocalService.getGroup($themeDisplay.getCompanyId(),"Guest") )
#set($pageLayout=$layoutService.getFriendlyURLLayout($selectedPageGroup.getGroupId(),false,"/search"))
#set($plid=$pageLayout.getPlid())
#set ($my_sites_portlet_url = $portletURLFactory.create($request, "3", $plid, "RENDER_PHASE"))
<div id="search">
<form onsubmit="ctem_3_search(); return false;" name="ctem_3_fm" method="get" action="$my_sites_portlet_url">
<input type="hidden" value="maximized" name="p_p_state">
<input type="hidden" value="view" name="p_p_mode">
<input type="hidden" value="/search/search" name="_3_struts_action">
<input type="hidden" value="$themeDisplay.getURLCurrent()" name="_3_redirect">
<input type="hidden" value="0" name="_3_groupId">
<input type="text" value="" placeholder="I'm Looking for..." size="30" name="_3_keywords" class="">
<input type="image" border="0" align="absmiddle" title="Search" src="/iu-health-theme/images/custom/ui/background/background-header-search-button.png">
</form>
</div>
But If you want to embed search in theme and want to redirect on specific fix community page then you may need some modification and can use below code in you theme .vm file :
#set ($layoutService = $serviceLocator.findService('com.liferay.portal.service.LayoutLocalService') )
#set ($selectedPageGroup = $groupLocalService.getGroup($themeDisplay.getCompanyId(),"Guest") )
#set($pageLayout=$layoutService.getFriendlyURLLayout($selectedPageGroup.getGroupId(),false,"/search"))
#set($plid=$pageLayout.getPlid())
#set ($my_sites_portlet_url = $portletURLFactory.create($request, "3", $plid, "RENDER_PHASE"))
<div id="search">
<form onsubmit="ctem_3_search(); return false;" name="ctem_3_fm" method="get" action="$my_sites_portlet_url">
<input type="hidden" value="maximized" name="p_p_state">
<input type="hidden" value="view" name="p_p_mode">
<input type="hidden" value="/search/search" name="_3_struts_action">
<input type="hidden" value="$themeDisplay.getURLCurrent()" name="_3_redirect">
<input type="hidden" value="0" name="_3_groupId">
<input type="text" value="" placeholder="I'm Looking for..." size="30" name="_3_keywords" class="">
<input type="image" border="0" align="absmiddle" title="Search" src="/iu-health-theme/images/custom/ui/background/background-header-search-button.png">
</form>
</div>