Instructions
Travel to Farmer Fred's house. It's located just north of Lumbridge.
Enter his house to find the shears. Take them, and use them on three of his sheep to get their wool.
Harvest two onions from his backyard garden.
Head south to Lumbridge. Enter the castle and climb to the second floor. You'll find a spinning wheel here. Use the wool on it to make three balls of wool.
Travel to Draynor Village. It's just west of Lumbridge.
Visit Ned's house the in middle of town. Speak with him and ask him if he can make something out of wool. He'll tell you he can make a wig. Agree, and he'll take your three balls of wool in exchange for a wig.
Go to Aggie the Witch's house, which is just west of Ned's place. Give her the onions in exchange for yellow dye.
Use the yellow dye on the wig to make it a blonde wig.