Wall Street opened higher in early trading after a massive sell-off and as the government announced details of a program designed to boost availability of credit. The Federal Reserve plans to lend up to $200 billion initially to spur consumer and small business borrowing for autos, education, credit cards and other expenses. The central bank announced the plan late last year. Some rebound has been expected because of the heavy selling seen Monday that sent the Dow Jones industrial average below 7,000 for the first time since May 1997. The Dow was up 79 at 6,840. The Standard & Poor's 500 index was up 10 at 710, and the Nasdaq composite index was up 20 at 1,343.