You need to be listed on the local MLS by a RealtorÂ® to be posted on Trulia. There are many other sites that will take your money to post your home for sale.
Be aware that the vast majority of buyers use a RealtorÂ® to help them with their purchase and most sites other than the local MLS fly under the radar. When I have a buyer I do not check the hundreds of sites where people can post a home for sale. You could spen days and find nothing but properties that got tired, listed with a RealtorÂ®, and sold 2 years ago.