Tap the round blue arrow button to edit an existing yarn.
Tap the edit button if you need to add or delete a yarn. (See next screen shot.)
Tap the red round minus button to delete a yarn.
Tap the plus button in the titlebar add a new yarn. (See next screen shot.)
Enter the name of the yarn and tap next.
Select the "put up" of the yarn from the picker wheel and tap next.
Enter the length from the yarn label and tap next.
Enter the weight from the yarn label. Tap Return.
Tap the appropriate units for length and weight. Tap done.
Tap Yarn Estimator to return to the main menu.