First you need a service and repair manual, link above, this will show you exactly HOW to do it, and what parts are required.
Now you can usually get the parts pretty easily, from eBay, or indeed direct from Acer, or one of it's many parts suppliers.
To simplify, what is in the manual, You simply remove the screws according to the manual, then you remove the keyboard, and then remove the screen surround. Remove the Old LCD and replace it with the new, usually they simply plug into a socket on the motherboard.
Also there are tree parts to a "Screen" the Inverter, the backlight and the LCD/TFT itself. Now make sure that you have identified exactly which part is faulty... as it maybe the any or all of these. use the service manual to isolate what is what.
of course this is only if the screen is unbroken etc. If it is just Dull, or no image at all, then it may only be the inverter or backlight. If however you were getting weird colors green or sparkles or colored segments and weird displays then that's most likely the screen itself.
In any event it is a pretty easy fix, it can be very fiddly, and one must take care of the cables, and the sockets they must be removed very carefully, and replaced the same way, always be mindful just how delicate these cables and sockets are.
below is a link that shows you a generic how to do it...