Who?
Users of your site
As previously noted, your web-space will be publicly accessible, and could therefore be read by anybody. It is a good idea, however, to consider the main readership groups you wish to target, and prioritise these carefully. This will enable you to ensure the best quality and quantity of information to provide on each page, as well as the overall layout of your site (using the drop-down menu).
Users of your intervention
As a garment, designed to fit everbody, will fit nobody particularly well, your intervention is likely to be ineffective unless you are very clear about the type of people you most wish it to be of benefit to. Remember not only to consider the service-users, but also practitioners and fundholders who may wish to implement your intervention within their own service.