Your replacement display may come with colored plastic film on the back of the LCD. If so, use the pull tab near the home button to peel the plastic film from the LCD before installing the new display in your iPhone.
After reassembly, clean the touchscreen surface with an alcohol wipe prior to turning the iPhone back on. The alcohol helps dissipate any lingering static electricity, which can cause problems with the display.
After reassembly, protect your new display from any scratches by installing a new screen protector.