People are not accustomed to going to a charity, company or church web site to search and adopt needs. They are used to hearing about charitable needs or events through emails, a bulletin, the pulpit announcements, etc. and signing up via a paper form. So you will want to communicate and remind them frequently to go to your web site to find ways they can serve others. Driving traffic toward your web site will take workload off your staff and allow you to spend more time cultivating relationships and planning new opportunities to increase your impact in the community.