e-commerce site

Hello everyone , its pleasure to be a part of this community as the members are very helpful and open to newbies.. As for my comcern i ma new user myself and very interested in building an e-commerce site. I have two major problems. 1.How can i put contents ike categories with subcategories dropdown option and 2. How to put search option for places in which users can search things in their own locality.. Hope you guys will help me with this regards..