You need to publicise your product/image/event on mass media like Radio. Write a request letter to the broadcaster. In your letter  Say about the matter you want to be aired and the people to be addressed.  Say about the preferred timings along with per blast and the campaign duration as a whole. Say about your budgets for the air-time inclusive of the art work.

Dear Mr ABC: We are on the verge of launching a radio-ad-campaign for our social media and news channel apps. The latest on the spoken one is ‘Wear your attitude’; an app for free to try big brands, Indian and international, virtually on you. The target audience for the product is unisex, and it is spreading from 20 to 50 years of age: urbanites. The people of this demography get activated on radio from 8 to 10 am and later in the day around 6 -9 pm. Our planning is to give six blasts of twenty seconds each during the given time slots of the day between October the 1 st and December the 31 st. Sir, our funds for the same are limited; however, we are open for barter against the airtime and the artwork concerned. If you agree to the given proposition, we can incorporate your esteemed radio station on the ‘channels of preference’ in our app. This will give you an exposure of around one million subscribers that we have on our social media platform. I look forward to hearing from you in confirmation. Yours sincerely, xyz