First of all, To Install NetBeans 8 in your computer go to [NetBeans Web Site] and download that version that you want in my case I am going to choose the PHP version.
Secondly, Open your terminal and type the following command:
chmod +x /Downloads/netbeans-8.1-php-linux-x64.sh
Then, type this command in your terminal as well:
cd ~/Downloads && ./netbeans-8.1-php-linux-x64.sh
Finally, you should see a netbeans wizard installation.