I kinda remember I used some pictures of stars and stuff like that to get that texture, you put them in overlay and play around with diferent opacities, the same goes for the circles, three white circles with diferent opacities, then you use a nice color pallete to use it with "colour" and pretty much that is. Also don't forget to play around with light (white brush) and darkness (black brush) to get your light and shades wherever you need them. Sorry for answering so late!
Nice job! It's really well done. But i have a litte question... can you make an invitation for me? You can use this one, you only have to change the text. Because i searched desperately for a nice birthday invitation and i couldnt found one. Till i saw this one!