Advertising on this forum.
For this we have the Free Adverts section.
Obviously pubs, clubs and other organisations that serve the community can inform members of their activities in the appropriate sections.
Beyond this the best way to promote something is by making your website into your signature. Then it will appear at the base of every post that you make. This not only drives traffic directly to your site, it also improves your search engine performance.
Other than the above advertising is frowned on and will be deleted.