As Laura said Trulia is for agent only listings. There are alot of sites available to you, zillow is one and there is always for sale by owner .com. Do your research.
Keep in mind if you use a realtor we not only understand all the legal aspects of the real estate process, we know all the latest ways to market you house to get it the maximum exposure you need it todays market.
Good luck to you!!
Trulia does not accept for-sale-by-owner listings so that's the reason the site won't allow you to post your house. Only real estate agents/brokers can list homes for sale on Trulia.
However; Zillow.com and Craigslist.com will allow you to post your home. If you work with a real estate agent then he/she can give you the largest amount of exposure out on the internet. Something to consider...
Good luck selling!
Prudential Connecticut Realty