Cap Highlighting Help

I am in the process of growing out an "Inverted Bob" or "Reverse Bob"... Here's kinda what it looks like right now....  It's a little longer now, the bottom layer is to my shoulders... but the color is the same... Wish I had a picture of the back...



Anyway, I have been highlighting and coloring my own hair for years... I usually use foiling to do my highlights, but I'm looking for a less chunky, more natural look.  Basically, my hair is very dark, and as much as I've tried, I can't go blonde, it doesn't end well... So, I'm trying to lighten my hair up a bit for what's left of the summer with some nice highlights.

I bought the L'Oreal la Petite Frost Kit... This one as a matter of fact...



I know how to use it, but I do have a question....

With the way my layers are in my hair... especially in the back where the shortest layer is about 5 or 6 inches shorter than the longest layer, what technique should I use?  Should I frost it only on the top layer? Or should I frost it all the way through?  I also wear my hair up quite a bit... So I know I need to do the front of my hair as well...

You can either answer me on here, or I'm on Yahoo Messenger... Lucynshiney

Thanks in advance for any advice :)