Google is your friend. Start by searching case management elderly then look at what your competition is. That will get the ideas flowing. Find some people already in the business that you want to pursue. Get brochures from those companies on the services they provide.
In regard to online presence, a simple web app with contact information and details about your services can get you started. It can grow into a membership type site as well. I am a programmer and do web development, so if you have any questions I'll be glad to answer.
Check into business and professional licensing, insurance, etc. that are needed. Get a federal tax id, a business bank account, and most important a business plan. Google business plan sample for a start.