Is your home listed with a Realtor? If so, they can log-in and upload unlimited photos.
Not sure for a For Sale By Owner? Have you tried to create a log-in? Look up and to the right on the green bar. There should be a spot that would allow you to create a log-in. Once you do that, you should be able to upload photos.
Trulia does not charge Realtors for this. They are using our MLS listing data so it works out for them. A For Sale By Owner...again, not sure.
In the end, you will be much better off listing your home with a Realtor. Your likely to get 5%-10% more on sales price (study by National Assoc of Realtors), a smoother closing and assurance all the required paperwork and disclosure were used. We make you more money and keep you out of trouble.
Need a referral? Let me know. I always recommended seasoned agents that are members of the ERC (Employee Relocation Council) and handle relocation clients moving into Nashville.