Welcome to Trulia! You can update the photo on your profile within the Account Settings section of your My Truli account. Access the link below to navigate to that section directly. Once there you should see a link under your current photo to 'Change photo'.
Please let us know if you have any other questions, or if you ever have any general feedback for us.
By creating a Trulia account and claiming your listings, you've already done it. Take a look at your listing below for example - you should find your photo and contact information on the page if you scroll down just a bit.
If you want to claim other listings of yours that are on our site and add your information to those properties, you can use the search box located in the My Listings section of your account or you can simply find your listing on Trulia as a buyer would - you'll then see the option to add your contact information to the listing on the right side of the page.
I hope this answers your question. If not, or if you have any others, please let us know.