Step by step

Mix until well incorporated into the sauce, then add a little pepper and a ladle of water from the pasta cooking pan

Truffles should be stored in the refrigerator wrapped in a paper towel or cotton cloth in order to allow it to retain its natural moisture. Note that black truffles keep longer, while white truffles will keep their essential characteristics for not more than a week.
It appears that the name "truffle" comes from the Latin "terra tufule tubera", as truffles resemble tufo, a porous stone which is common in Italy.