There are forum websites in almost every niche. Discussion Forum are generally a question answer type website where people of similar interest discuss with each other. Most of the forum sites have option to add signature on each of your answers or questions posts. Signatures are generally a common text which will appear along with all your posts.
So, You can use that signature field to add your website URL or use it from branding. Once you have added your website URL in signature then it will start showing at the end of each post of yours in that forum website. So, the more quality answers you write, the better will be chance that people end up reading your website.