There are only 4 screws to remove, once the back cover is off, there are no more. You need to carefully lift the front case off the 4 places where the screws were, lifting gently at the bottom to clear the motherboard from the top (where the SD card slot is). Be careful, at the bottom of the case is the ribbon cables for the LCD screen, damage these and there is no return.
This gets the front cover off. You can gently prise the LCD off the casing then, be very careful. Use compressed air (if you have some) to remove the dust from the LCD screen - don't touch the screen with your finger; any grime or grease will look awful.
As always, you are entirely responsible for anything you do to your machine, your risk entirely, all the Forum can do is give you advice. If you don't know what you are doing, don't do it, unless you are prepared to take a risk.