Have a google for Glitter Styles Photoshop. I am not saying this is the best but it was the first one that came up on the list.
Once you have downloaded and extracted the .asl file select the layer that has the text, shape or graphic etc. that you want to apply the glitter to.
Click on fx at the bottom of the screen
now click on the word styles at the top of the dialogue box
Select load styles from the options icon and navigate to your downloaded .asl file
this will load the new styles to the end of your existing ones (a bit like when you add brushes)
All styles are are a set of presets for the different fx, so you can go in to the different fx and change them to your liking - such as colour or pattern.