Heat oven to 375°F. In medium bowl, combine beans and chiles; mix well. Spread 2 to 3 tablespoons bean mixture onto each tostada shell; place on ungreased large cookie sheet. Bake at 375°F. for 5 to 7 minutes or until hot.
Meanwhile, in large skillet, brown ground beef; drain. Stir in 1 1/2 cups of the salsa. Cook over medium heat for 2 to 3 minutes or until thoroughly heated.
Serve tostada shells topped with hot beef mixture, shredded lettuce, cheese, tomatoes and remaining salsa.