Expansion unlock 301 stars done in color green what does it mean?

You are probably talking about land expansion. When you tap on a lightly clouded plot and select the green button, the game shows you what the star and compass requirements are for that plot. So you need 310 total stars to unlock that plot. To see how many stars you currently have, go back to your island and tap on the cash register. Your star count is shown in the upper right corner. The star count accumulates every time you complete a star playing regular scenes (5 stars max per hidden object scene). It is a marker of your game progression, so it never goes down.

In general, to unlock new scenes, you need to add more Flowers to your island. Every decoration has a Flower value. You may have enough in storage and just need to place the decoration on your island. If not, and you have to buy decoration, be aware that you have to wait for the construction to be complete before the Flower value counts. The greater the Flower value, the further you can get in the game before running out of island space.

In addition to the Flower requirement, before you can travel to a new chapter, you need to find all the story clues (2 per scene = 10 per chapter), earn 20 stars from that chapter, and complete the adventure scene at the end of the chapter.