Design an Advertisement

We need advertisement banners for our facebook page for a new product planning to launch in last week dec 15. This is an online classfied website to sell/buy old mobile phones we need to create some target audience in the initial face of launch advertisement should be attractive, explain the product and create audience. we need 50 ads to be posted on facebook page when we launch Rs 100 per Ad total 50. 100%50=5000