First, clean and wash your hands, let it dry and apply a good base coat on all your nails :) Ok, let the base coat dry first. When its dry, follow the following steps:
Step 1: Grap a clean sponge and cut the sponge into small pieces. You only need one piece.
Step 2: Apply some white nail polish on the sponge ( not too much, otherwise you won't get the sponge effect)

Step 3: Dap the sponge on the tips of your nails. Do this to all your nails and let it dry. Can you see the sponge effect?

Step 4: Apply some glittery nail polish on the tips of your nails and let it dry. I have used the colors gray and yellow.

Step 5: Apply a top coat and you're done =D!

I have used a white nail polish of the brand: Dear'Lee and glitter gray and glitter yellow nail polish of Catrice.