This photo shows you how the pocket will look when it is completed. It has boxed corners at the bottom so that it will have room for larger items such as a cell phone or disposable silverware. It is also the perfect size for a travel pack of tissues. If you would like to use the pocket to carry standard sized silverware, I would add two inches to the length of the pocket piece and adjust the placement of the pocket accordingly.
Using your iron, press the edges of the pocket over toward the wrong side 1/4 inch (a sewing gauge makes it easy to measure your seams). One on edge, fold over another 1/4 inch; this will be the top hem.
With matching thread, sew across the top edge of the pocket close to the first 1/4 inch fold to secure the hem. Press all edges again to ensure that they are flat for the next step.
In this step, we are going to create the boxed bottom of the pocket. Lay the pocket piece right side up with the hem at the top. Hold the bottom edge of the fabric while folding the right side downward in a diagonal manner. Match the right edge of the pocket with the bottom edge so that the folded edges align. Using a ruler, mark a line perpendicular to the bottom edge that is 1/2 inch from the point. Make sure the line is straight or your corners will be crooked. Repeat this step for the bottom left corner. After you have marked both corners, pin them in place for sewing.
At each corner, sew along the line that you marked (don't forget to remove the pin as you approach it), backstitching at the beginning and end of the seam to secure it in place. Flip pocket right side out. The photo shows how the pocket bottom will look when it is done.
Find and mark the middle of the top and bottom edges of the pocket by folding the pocket wrong sides together and placing a pin at the fold line. Set aside pocket for now.
Now we are going to mark the pocket location on the lining piece. Fold one of the tote bag lining pieces in half so that the left and right sides match up; place a pin at the top center and bottom center of the piece (as you did for the pocket in the step above). Using your marking tool and a ruler, mark a line down the center of the lining piece starting about an inch below the top and ending about an inch above the bottom edge.
Now, measure down from the top edge 2 1/2 inches and draw a line parallel to the top edge that extends past the center line about 2 inches on each side. A clear quilting ruler or square ruler makes this easier, but if you don't have one, just measure 2 1/2 from the top on either side of the center and mark; draw a line that connects the two marks. On both sides measure out from the center line 1 3/4 inches and mark. To mark where the bottom of the pocket will go, draw a line 4 inches below the top line. I have shown the dimensions on the photo to clarify where all the lines and marks should be.
Starting with the top edge of the pocket, pin the top center to the center marking line where it intersects with the top line marking. Bring in the sides of the pocket so that they match up with the markings 1 3/4 inches from the center (the fabric will have a bump between the center and outside edges; this is intentional).
At the bottom edge of the pocket, match the center pin with the center marking at the bottom line as shown here.
Place additional pins around the edges to hold the pocket in place. Pin the bottom corners so that the corner itself sticks up from the surface. Also make sure that the corner seam on the inside is not pinned into the seam on either the top or the bottom. It will create too much bulk to sew over.
Take your pinned pocket over to the sewing machine and stitch around the pocket 1/8 from the edge. At the top edge, backstitch more than you would normally to reinforce the seam at this stress poing. Stitch slowly around the pocket so that you can pull the pins and keep your stitching consistent and neat.
When you approach the bottom corner, push the boxed seam down and away from your stitching. Stitch down until you are 1/8 inch from the bottom edge. Leave your needle down in the fabric and turn the pocket so that you can begin stitching across the bottom.
Before you begin stitching across the bottom edge of the pocket, push the box corner away from the seam again and stitch across the bottom. Repeat these steps as you sew around the other corner. When you reach the end of the seam, backstitch several times to reinforce the seam as you did in the beginning.
Here is a close up photo showing how the corners will look after they have been sewn. This process looks much more complicated than it really is. The most important thing is to take your time and use a lot of pins to keep the fabrics from shifting.