The 20-year-old Spanish forward signed a long-term deal with Premier League club from Sevilla on Saturday.
"I feel like I'm in a bubble at the moment," Alberto told the club's official website.
"For me Liverpool is a top team. I feel like I am dreaming and I want to enjoy it to the full.
"I feel very excited, I've never felt so excited before but I'm very happy. I think I am the happiest man on earth."
Liverpool start the new Premier League season at home to Stoke City on August 17.