Social media buttons in new windows

I have read somewhere but can’t find it now so am asking hoping someone can just direct me to the right link or advise me how to do this.

I want to open windows whenever clicked on any of the social media buttons on top right corner of the site. Where exactly do I used that “target” code and in which file? I have tried this in the past but it didn’t work but now I need to get it done. Thanks. Hare Krishna