If you can not edit your hosts file located in “private/etc” directory, it’s because;
The whole directory has “admin” permissions, and your text editor maybe running with your current user permissions. You can either move the Hosts file to desktop and edit it, and put it back, or use Terminal and edit the file.
Open Terminal.
Type cd /etc
Type sudo nano hosts
Type your password
Edit File
Hit Ctrl + O to save
Hit Ctrl + X to quit