This stage is Chain-Link Charge (3-2). This complete walkthrough will provide you with a 100% video playthrough and a screenshot of where you can find all the green stars.
Game Play Walkthrough Video
Green Star 1
You won’t miss this green star. Use a Cat Mario to climb on the fence to get it.
Green Star 2
When you see the mystery box that take you to the next section of the stage. Do not go over yet, just to the right platform to claim your second green star.
Green Star 3
The Cat Mario is also needed for the last star. You will see a cat paw wheel where you can raise a platform. The last green star is on top of the raised platform.
When you get to the transparent tube, do not go through it. Climb up the blue fence and grab the stage stamp.