The service of running campaigns where you pay to have an advert, such as Google Adwords, these are showing up on this website as sponsored links on the right hand side of the pages. You can also do this in social media such as Facebook to get your website advertised or your Facebook page or both. You can target your adverts to specific audiences and demographics.
There are lots of online directories, some free, some paid for. Like a hobby magazine that you purchase from WH Smiths some sites are specialised and have a niche audience so paying for adverts on these sites could get you in front of a lot of people already interested in what you have to offer.
I can help you to decide which of these are most appropriate for your business and help you to set them up.