Start by filling in the crack with glue and letting it dry. Depending on how badly cracked your cone is it might take several applications. Remember to get both sides top and bottom of the cone filled with glue. Next take a piece of the coffee filter and cut it to size so that it covers about a quarter inch to a half inch on every side of the crack. Try and tear the coffee paper whenever possible instead of cutting it. This helps the fiber bond to the cone better and prevent the edges of the patch from peeling up over time. now use your paint brush and glue the patch on. Apply a relatively liberal amount of glue to the top and bottom of the patch patch as well as the cone it's self. Once your done it may be a good idea to go back around and put some more glue around the edges of the patch to keep it stuck down. You can now let the glue dry. Genially you sould only need one layer of the coffee filter patch but in high wattage applications like large subs I recommend adding a second layer of the patch for safety.