For the first part, since you know that 4^2 in 16, which is your area, then the 2 sides are 4 square yards and 4 square yards. For the second part, you know that all sides on a square are equal so if one side is 4 square yards, then so are all the other sides. As a result, 4 times 4 is 16, your perimeter.
Final Answers: Part 1 - The length of one side is 4 yards.
Part 2 - The perimeter is 16 yards.