Set documentroot (apache2)

Hi in default configuration file of apache i have insert this:
Alias /miro "/var/www/tesi/public"
<Directory "/var/www/tesi/public">
  Options ExecCGI FollowSymLinks
  AddHandler fcgid-script .fcgi
  AllowOverride all
  Order allow,deny
  Allow from all
</Directory>

in .htaccess file i have insert:
RewriteBase /miro/

if i launch http://localhost/miro
it works but the ilnks in the page send to http://localhost/link and not
http://localhost/miro/link

How i can do to set miro like document root?
Thanks