I came acorss this picture online, but i'm not sure how to achieve it, its not overlay right? I think.
The easiest way to slice the text up which I think is what you are having trouble with is fairly simple:
Its really two text images on top of each other so you'll need to take the copy of the unsliced image lay it below the sliced image and erase the bits that you dont want to show.
That is just a straightforward use of the Letraset Shatter font (or a clone of it). Shatter is based on Helvetica (obliqued, rotated left, then sliced and displaced if you want to create the effect manually - something that's immeasurably easier with a computer than it was with rub-down lettering and an X-Acto knife); there are similar fonts available (at various prices and quality levels) for quite a few of the better-known display fonts, and in different shatter patterns.