1980 razz

i have an after market wheel on my vette ..it basically allen key right on with no guts inside to where the old wheel was.i think it is a gt or something like that..i see them for sale at checkers and other auto stores all the time.it was like this when i got it..what do i need to do to get a horn hooked up..ive caught myself reaching out to honk at idiots on the road only to have nothing there..i dont think they can hear all my yelling so a horn is a must..any ideas anyone??