2 more stars

Well your not the only one I also have two stars left for mario but there differnet levels from yours. Now I'm going to do this step by step so it's easier to understand.
So first off the hidden star in deep dark galaxy;

Step:1
Go to Deep dark galaxy(well duh)

Step:2
Go to the first level

Step:3
Go through the level as per normal but when you reach the lake go all the way to the bottom not the usual way

Step:4
Grab a green shell and blow up the mines near a sunken old ship.

Step:5
After blowing it up a slingstar appears while dodging the mines shake near the star

After doing this you will be flung down the bottom of the cave looking section of the galaxy and into the box you can see at the begging of the level.

Step:6
Once in the box you see a boo with a star in it

Note these next steps are only if your desprete to know how to kill boos but it is kind of obivous

Step:7
Jump on the stuff coming out of the walls and jump at the top and shake the arrow to be tossed to the left. Then jump on the hamburger thingy and shake the arrrow again. Finally once again jump on the roof hamburger one and shake to be flung to the right.

Step:8
Once on the right smash(shake) the glass ice thing to make sunlight come in

Step:9
Well killing boo isnt so hard but getting back is harder. Once you kill boo go jump into the bubble making thing and shake in time to shake into the arrow to be flung down once again

Thatsall

Okay so now for Dusty dune
If your wondering why this is in a differnet answer because the other one was too long.

Step:1
After going to dusty dune go to level 3

Step:2
Go through the level as normal until you reach the planet with antenas on it instead of going through the normal star instead kill all the enimies actually thats optional but it helps but what you realy need to do is hit the ground oound wood block thin gand music notes will appear do the usaual thing and a star will apear shake and be whooshed away

Step:3
And then it's kind of obivous so yeh

Thats all

Go to deep dark galaxy's lake where you raced the killer whale guy, and destroy the mines with a green or red shell, then enter the new path, and solve the light-based puzzle on the next planet. go to dusty dune galaxy's moving sand planet(that one where the sand goes up and down and that has antennae) and ground pound all the wooden circles insted of progressing normally, use the launch star and continue until you get the star.

Hope this helps!!!