you have to edit the template your using, templates are in the /lib/tpl/ folder. Usually the file that contains the create page button is the main.php
the code to insert is something like
<a href="<?php echo wl('your:form:id:page') ?>">Create a new Page</a>
if you want to remove the default "create new page" butten you have to remove the
<?php tpl_button('edit')?>
from the template.
see also
http://www.dokuwiki.org/devel:templates