You can create the greatest web site in the world, but it won't do you much good if people don't know about or can't find it. Promoting your web site is an integral part of making it a success.
Some people mistakenly believe that if you simply submit your web site to the major search engines, that's the extent of promotion, but in reality, there's much more to promoting your web site effectively.
Just as many businesses do, the first approach to promoting your organization's web site is to associate the web site address with every printed instance of your organization's name: signs, newsletters, flyers, business cards, advertisements, etc. The goal would be to make the two synonymous in people's minds. However, this would require, I assume, that your web site address be relatively simple and obviously related to your organization's name.
Make sure that any existing community that lists your organization gets updated information, including your organization's web site address.
It's probably also a good idea to identify local online community directories, and submit your web site for inclusion in the proper categories. In Austin, TX, for instance, we have three major local directories: Austin.CitySearch.com, Yahoo! Austin, and Austin360.com. If you live in a smaller town or rural area, of course, you may not have such sites. Other possible sources for locating local directories would be your local newspaper, Chamber of Commerce, tourism board, etc.
In writing this article, I did a quick test search on Google for Austin Texas churches. My search returned quite a few local and national directories of churches. You should be able to apply a similar search to find places to submit your organization's site.
In promoting your site locally, don't forget to use good ol' fashion networking. Swap links with other local congregations of your affiliation; ask members of your congregation to post links on their personal web sites.