Somebody just asked the same question, so here is the same answer -
Trulia works thru Realtors / Brokerage firms and there are a few ways to get the listing in the system:.
If your realtor's company has a direct feed to Trulia, then you are set, you don't have to do anything (how my listings go on Trulia).
Or, if his/her personal site has syndication with Trulia then that will feed into Trulia also
There are two ways to get your listings on Trulia. The Realtor can submit your web site address for crawling by the Trulia search engine or if you are familiar with xml you can prepare and submit a listing data feed with your listing information. ; here is a link http://www.trulia.com/submit_listings/
Sometimes it takes a couple of days for the listing to show up, I guess when you are crawling - good description for that.
Now that I answered your question, my question for you is do you have a Realtor to help you? If not, can we recommond one to help you with this and many other questions you might need help on?