Seeing as this might get confusing, I will bullet point each step you need to take. Or watch the video at the bottom.
1. Start the game and head straight to the workshop.
2. Choose the crayon and use it.
3. In the land of the fables, head north and find the next crayon, then use it.
4. Pick up the paint brush by the easel and use it.
5. When you arrive back in the house, head to the SW corner and find the red paint. Use it on easel.
6. Walk left past the easel and down a narrow corridor. Follow the path all the way round.
7. Look at painting on ground, then turn around to the bookshelf approaching you.
8. Continue and push the basketball up the hill.
9. Walk over the bridge to reach the paint.
10. Continue the path to reach the easel again. Interact with it.
11. Look to the right of the easel and pick up the picture on the ground by the chair.
12. Then pick up the crayon and use it on the easel.
13. You'll be back in the fable lands. To the NW of the easel is a sword in a rock. Hold
until you have it.
14. Go near the serpent and your achievement will unlock.