Boil chicken, onion, celery & salt until chicken is tender. Remove chicken from broth and cool, remove bones, chop chicken. Boil broth down to 1-1/2 c & add soups & mix. Preheat oven to 350 degrees. Arrange tortillas in pieces in bottom of buttered 8 x 12 in casserole with tortillas pieces. Cover tortilla pieces with chicken chunks. Sprinkle with green peppers. Cover with Ro-tel tomatoes. Pour soup mixture over all of it. Cover with foil & bake 35 to 40 min. Remove from oven and remove foil. Sprinkle with cheese, return to oven, cook til cheese is bubbly Serve hot.