Use your fingers to flip the plastic ring so that all of the "spikes" or pointed grips face the outside.  Push on the inside of the ring on one side using your thumb.     Once you manage to flip the inside out in one spot, it should be easier to gradually ease the rest of the inside outward.     Note that the pointed grips may "bite" or pinch into you slightly as you work. Typically speaking, though, the edges are not sharp enough to cause any cuts or wounds.    Wiggle the ring over the outside of the cap until it fits snug around the center of the cap's perimeter.  Rest the ring on the top of the cap, aligning the opening of the ring with the top of the cap as accurately as possible.     Use your thumb to push down on one side of the ring until it slips over the edge of the cap.     Gradually ease your thumb around the perimeter of the ring to slide the rest of it onto the cap.     Once on, ease the ring to the center of the cap by sliding it down with your thumb and forefinger.    All the spikes on the ring should stick out.  Carefully run your thumb along the spikes in the opposite direction of the spikes. Doing so should lift the spikes nearly straight up.     Note that you may scratch your thumb in the process of doing this.    Your ninja star is now complete. Do not throw this ninja star at animals or people. It is not a particularly dangerous version, but you can still cause damage if you throw this at an animal or human.

How would you rephrase that briefly using Indonesian?
Putar balik cincin sehingga bagian yang seharusnya berada di dalam menjadi di luar. Masukkan penutup botol ke dalam cincin. Atur ulang bagian yang tajam jika dibutuhkan. Kagumi hasil kerja Anda.