Banner Ad Plugin

Hi there, just a quick query, I was wondering if anyone would be able to guide me. My site has been up and running for a week now, and its gathering in popularity. In the not too distant future I will want to add a plugin for banner advertising and charge a small CPM rate. Currently this is just a personal venture, but my aim is to produce a small income from it, if only to fund further development etc. I really want to be able to chose the customers, this is a niche market and I want the ads to represent that. Also it is my first website venture so a plugin that is as ‘point and click’ simple as possible to use is required. Thirdly, I am looking for a plugin that ticks those boxes and is free. ?? If anyone would like to take a look at the website before they advise… the link is here: https://www.equiviews.co.uk/blog/

Thanks in advance for any help on this