Spencer McClay stands out in Grass Valley. And not just because of the color of his skin. McClay is black and walks everywhere he goes in a county where 94 percent of the residents are white, according to the U.S. Census Bureau’s 2010 figures. “I wasn’t sure if we were going to fit,” said Gretchen Serrata, McClay’s adoptive mother. “I don’t even think about it,” McClay said. “I do what I have to do.” Whether to his downtown art studio or on his way to help teach at the Neighborhood Center for the Arts, which provides creative opportunities for adults …