Iron the pillow cover from the inside to ensure there are no wrinkles, or toss it in the dryer for a few minutes (check the tag to see if it can go in the dryer). Trim the end of the yarn.
Start placing the yarn on the pillow cover in the shape of the word.
Continue adjusting the yarn until you are happy with the placement, then snip off the excess. Remember to leave a couple inches around the letters to make sure the word is readable once a pillow is in the cover.
Glue the yarn onto the pillow cover, working with a small section at a time. Roll a few inches of yarn to the side, place glue on the pillow cover, and press the yarn back down.
Use plenty of glue to make sure all of the yarn is glued down. If there are any bare spots, add more glue.
Allow the pillow cover to dry for 24 hours before placing a pillow inside. Finished!