[TYPO3-UG Italy] (no subject)

[Nicola]

 Quando entro in typo3 inserendo user e password mi d ail sequente errore
“Important notice!
- The Reference Index table is empty which is likely to be the case because
you just upgraded your TYPO3 source. Please go to Tools>DB Check and update
the reference index.

It is highly recommended that you change this immediately.” 
qualcuno mi può
dire come posso correggerlo?