Mark equidistant points along the top and bottom edges of the lampshade. Connect the points with diagonal light pencil lines, forming Xs around the shade.
Working in one direction, glue wide ribbon over the lines. Trim the ends and glue them to the inside of the shade. Hold the ribbon in place with clothespins until the glue dries. Center the narrow ribbon over the wide ribbon and glue it in place. After the glue dries, repeat the process in the other direction to complete the X patterns. See the photo for details.
Using an awl, make a small hole in the center of each ribbon X. Insert a small brad into each hole.
Using the awl, make evenly spaced holes for the prisms along the bottomedge of the lampshade. Cut the wire into enough 4-inch lengths for each hole. Insert a wire length through the prism and make a loop to hold it in place. Curve the wire into an S shape and insert the remaining end through the hole in the shade. Trim the wire to the desired length, depending on the size of your prism. Loop the end back on itself to secure it.