Don't know what's missing to get horn

[jolobo64]

What should be in the steering column to get horn to work, I have original steering column and the turn signals work. I'm using after market steering wheel with adapter and one post horn button. When removing steering wheel there is one round white plastic piece and below it is another white piece screwed in that controls the turn signals and below it are wires. I have bought a new horn but I'm thinking a relay is missing or one of the wires coming to column need to be extended, I don't know just fishing here.