How do I advance after mastering level 10?

To advance, you need to add decorations to your island to increase the flower value. The number of flowers you need is shown next to your name in the upper left corner. Once that count reaches zero, you will level up to the next level (level 11), and the count will immediately show you how many flowers are needed to reach the next level. You'll also need to complete the adventure scene at the end of the chapter. Once you have completed both of those steps, you can then "travel" to the next chapter and play scene #11.

The game is a strategy of adding flower value to your island as you decorate. Buy too many decoration of low flower value, and you will run out of space on you island. So you need to balance it with decorations of high value, which for beginners, many be in the seasonal set.