Once you've created the faceplate and uploaded the new firmware, you'll need to affix the faceplate over the TIMESQUARE LED matrix.
To make sure you have the faceplate lined up correctly check that the text on the side of the LED matrix lines up with the left edge of your faceplate. You can also test out the orientation by placing the faceplate on top of the LED matrix while it's in Wordclock mode to make sure the right letters are being illuminated.
It helps to add a small strip or two of clear double-sided tape to the underside of the faceplate to help attach it to the watch. The edges of the faceplate can then be affixed using Scotch or some other type of adhesive tape.