Your classifieds website needs complete seo services i.e search engine optimization. SEO is essential for any types of online business and without this you can never lead your business into successful.
SEO services consists of technical site audit, keyword research, on page optimization, off page optimization especially content marketing and finally social media integration, management and marketing.
Once you start seo, you can see visible improvements in a few months, which will keep on improving in subsequent months. If you need instant traffic and adds to display at your site, best option is to go for paid press release, social media promotion and PPC etc.