Windsor resident Cameron Mills was chosen to compete in the Big Country’s got talent contest at the Stampede in Greeley on June 25.  Cameron, the son of Pamela and Doug Mills of Windsor, played his guitar and sang three songs on the Big Country 97.9 Entertainment stage at Island Grove Park.  Cameron, 17, who will be a senior at Windsor High School, competed in one of the five preliminary contests and came in fourth in his preliminary round.  Three performers were selected from each preliminary night to advance to the Big Country’s Got Talent Finals on July 2 with the opportunity to compete …