Select your favourite contestant for The Voice 2014 in your profile
 

Select your favourite contestant for The Voice 2014 by going to 'User CP' (top-left of page), then Edit your Details and the name of the contestant will appear next to your posts.

Edit Your Details is also under Quick Links menu (top-right of page).

Have done, but 'The Voice 2014' didn't appear it was just a blank box?

Yeah, I've fixed that now.