Your gana get you clear polish or you can even get a polish that has color and just change it to be glitterie or a different color(blue polish + red pigment, blue polish + gliter, you get it.)
So your gana need any old or new pigment you want.
I made a paper funal so that its esaier to put the pigmet inside the polish. You just roll up a paper from one corner to the other and tape.
I started putting a metal little bead (if it doesn't have one) so that it breakes up the chunkes of pigment.
THERE YOU HAVE IT! Really self explanitory. Now just sot you new polish=)