How do radio sales people TV sales people and newspaper sales people get huge advertisers like Coke, Hardee's, Olive Garden, and the like to advertise on their media? I guess the question is... How do they contact the right people? Where do they get their names and phone numbers?
Most TV and Radio are owned by larger companies who may own 5-10 or maybe even more radio and tv stations/channels in different markets. You can inquire about them advertising with you through their corporate websites through email or more professionally by calling them but they are not going to advertise with you or sponsor anything unless it is very large and in that case most companies will have someone contact you before you contact them to inquire about advertising with you.
Listeners / viewers / readers make advertisers interested promoting their products to the radio/Tv audience Radio/Tv/Newspapers have advertising offers too and interested people contact them