Measure the square feet of each side of the porch. Measure the length and height of one side of the porch and multiply the two numbers to obtain the square feet of that one side. Repeat with the other sides of the porch. Add the measurements together to obtain the square feet of the porch. This is how much screen material you need. The screen must be the same height as the porch.
Place the edge of the roll of screen vertically along one post on one side of the porch. Line up the top corner of the screen with the top of the post and the bottom corner with the bottom of the post.
Staple the corners using a staple gun. Staple two or three staples between the corners to help hold the screen in place.
Pull and unroll the screen across the porch until you reach the other end. Make the screen tight.
Staple the screen to the top and bottom of the post. Add a few more staples between the staples.
Cut the remaining screen using a utility knife, cutting as close to the post as possible.
Staple the screen along the top and bottom posts of the porch, placing staples every 10 to 12 inches. If a post or two is in the middle of the porch, staple the screen to the posts.
Repeat with the other sides of the porch.
Cut a piece of trim to the height of the porch plus 3/16 inch. Cut the ends of the trim to a 45-degree angle.
Place the trim vertically on one post on the end of the porch, lining up the edge of the trim with the outer edge of the post. The 45-degree angle points inside.
Nail a finishing nail at the top corner using the nail gun, or hammer. Place a second nail at the bottom corner. Place nails between the corners, spacing them every few inches.
Cut more trim to the length of the porch plus 3/16 inch. Cut the corners to a 45-degree angle. Place the trim along the top of the porch. Line up the outer edge of the trim with the top of the porch so that the angle points down. One angle will line up with the angle on the vertical trim. Ensure that they touch.
Nail the corners of the trim and add nails every few inches along the trim.
Repeat with the other two sides, lining up the angles on the trim. Add trim to any posts in the middle as well.
Repeat with the other sides of the porch.