So basically, you just play this tune throughout the whole song. Add a capo if needed.
[ Tab from: https://www.guitartabs.cc/tabs/b/beyonce_knowles/halo_intro_tab.html ]
[------------------------------------------------------------------------]
[2-2-2-2-0-2----3-3-3-3-2-0----------------------------------------------]
[-2-2-2-2--------4-4-4------2---2-2-2-2-4-2-1---------------2-1----------]
[---------------------------------4-4-4----------4-0-4-0-4-0-----4-2-----]
[------------------------------------------------------------------------]
[------------------------------------------------------------------------]
