To block websites you should follow these steps in order.

Press the windows key and type Computer
and type this in the address bar C:windows/system32/drivers/etc

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you need Administrator Privilege to edit the file Hosts . you might even need to Allow your User to edit this file.
right click on the file Hosts and click properties, in the security tab look for your username and click edit (if you cannot find your username click on each of the options listed and edit them) now, tick the Full Control option and click Apply

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Now, you are ready to edit the file and block the website you want to.
open the file Hosts with Notepad

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Now at the end of the line put the cursor and press enter, in the new line type 127.0.0.1 ‘Website link’ for example 127.0.0.1 google.com now save the file Hosts (you can create a shortcut of Hosts on your desktop so you can block websites whenever you like right from your desktop). now head over to google.com, it won’t open.
remember to create a new line for each website.

Note:
if you are blocking facebook.com it will only block facebook.com and all its links, but will not ban m.facebook.com since m.facebook.com is totally a different website, you will need to create a new line and ban it likewise

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