The next step will depend on your replacement part.

If you have the screen assembly with frame, just inspect the parts: remove and attach any parts missing from the new part, for example the vibration module is to be pried up with a spudger and glued onto the new part.

If you have the LCD-Digitizer assembly, you will need to remove the old screen from the frame. This can be done by heating up the screen, and with the help of a suction cup and a razor blade, the screen should come off easily. The frame is then to be cleaned with isopropyl alcohol to remove all old double-sided tape.

Then proceed to apply new layers of double-sided tape and set the screen in place. Mind the cable routing.