Publishing giant Steve Forbes, promising a "new information-age campaign," Tuesday became the first person to announce his candidacy for president on the Internet. "Today I'm happy to announce the beginning of my campaign," Forbes declared in a taped audio address on his new website, www.Forbes2000.com. Forbes, 51, who tried and failed to win the 1996 Republican presidential nomination, is the fourth person to announce his candidacy for the party's 2000 presidential nomination. He follows traditional in-person announcements by Sen. Bob Smith of New Hampshire, conservative commentator Patrick Buchanan and former Tennessee Gov. Lamar Alexander. Al Gore is the top Democratic contender. Virtually all presidential candidates have their own websites. But Forbes was the first to announce his candidacy on his.