Well, the problem is several fold.
1. You want to set up a real estate site with listings.
2. You want others to be able to add to those listings. Are these others you speak of: Are they realtors within your same office or other realtors in your area? Or listings from an Association of Realtors in your area? How would you like them to be able to add listings? Through a form submission, direct upload of the properties being added, or using the databank of the Association?
3. You want search funtion capability within your site. What form would you like the search function to take? MLS numbers and other parameters particular to real estate, such as square footage, number of bedrooms, etc? In any event this will most likely require the setup of a database but it's helpful to know what is needed to know what to recommend.
These are questions that need to be asked and answered before you can know what you might need to set up the site. I don't think you can do much of this type stuff on Homestead and it may mean finding a new place to host the site and hiring someone else to initially set up a site for you. Free hosting sites such as homestead are often limited in what they allow, although I hear they have some paid hosting services which might be different.