Hi, From your 1line request, if my guess was correct then you need a website where you wish to sell banners. so the website will allow people to post their advertisement banners, or if they dont have the banner, your website(back office) will get the banner designed and same will be displayed in website. so the website will have multiple page, and each page will have the locations for banner appearance, you will set rate for different size banners and the duration of the banner to be available. Users register, select their position where to place banner, upload banner image, request duration, pay amount accordingly. Please let we know if your requirement is different from this.
Thanks