Do I need to attach my new LCD to the glass?

I recently bought a new LCD and Digitizer/Glass part for my iPod touch. I purchased them separately by accident (the LCD and Glass are NOT attached). I am wondering if i need to do anything to attach them together. The screen turns on normally unattached but the touch isn't working right now. Would this be an LCD or a Glass problem? Should I just purchase a new screen that is already attached?

P.S.

I got the glass from eBay and the LCD from amazon. Kinda wishing I would have just sold it as is with a cracked yet functional screen :/