How to install php extensions?

I’m a newbie at linux so I was wondering how would I install the php5-mysql extension? I found tutorials on how to install on google but I’m stuck at one step it say to add the line to /etc/php5/php.ini but easyengine doesn’t have folder ‘php5’ but it does have a folder called ‘php’ with two php versions inside it 5.6 & 7.0. How would I actually install php5-mysql extension if I’m using easyengine?

Can anyone help me? I’m still looking for solution