Measure and cut your foam sheets to 6-3/4 x 6-1/4. You'll need one for each letter of your chosen word, and an extra foam square for both ends of the banner as well, to add a picture.
Cut your white cardstock to 5-1/2 x 5-1/4. You'll need one piece for each letter of your word. The measurements don't have to be precise, but you want all the pieces to be the same size, and the cardstock pieces to be a little smaller than the foam pieces, so you're creating a bit of a frame.
Glue each piece of cardstock onto the front of each foam piece, one for each letter of your word. You can also use double-stick tape for this step as well.
Cut out each letter of your word, and glue it to the center of the white cardstock. The 475 font size I used fit perfectly on the cardstock, allowing a nice section of white space all around. If you're using a different font, you may want to play around with the sizes to get the right fit. Before I glued the letters down, I used a swirl paper-punch and punched out holes all around the perimeter of the letter to allow a bit more of the white cardstock to show through.
If you are adding foam pieces with a picture on either end (as I did with the ghost and the witches' hat pictures), then cut them out and glue them to the foam. Be sure to allow extra room all around so you can still see the foam square, for continuity when it hangs alongside the other foam pieces.
Using your regular hole punch, on the top of your foam square, measure in 2-1/4 inches from the left side and punch a hole (leave about a 1/4 inch from the top). Now do the same on the right side. You'll be using these holes to thread your ribbon through, to hang the banner.
Starting from left to right, thread the ribbon from the back of the tile into the first hole, straight across the front to the second hole. From the back of the second hole, you then thread it into the next tile. Continue until all the tiles are threaded, leaving a little bit of ribbon in between each tile, and a little extra ribbon on either end for hanging. For my five tiles, I used 53-1/2 inches of ribbon.