To learn how to find perimeters, it would probably be helpful to review the definition. So first open your book and check that.
Then, working under the assumption that the listed dimensions refer to the base, or "footprint", of the birdhouse, draw a picture of this shape, label the sides of the rectangle with the listed values, and add the lengths of the sides to find the length of the perimeter.
Note: You are probably (almost certainly) expected to simplify your answer to get "inches" to be something less than twelve. So make sure you do this simplification!