Surface area is the total area of the 2d cutout you have shown, because if folded it would be the area of the surface. Remember that each side of a rectangle has the same value on the other side. For example, where "2ft" is placed on the far left of the diagram, the side just to the right of it would also be 2ft. Once you have these values all written down, you can evaluate the area of each individual box within the entire diagram by multiplying the width by height. Once you have the area of each individual box, add all the area values together to find the surface area.
