Hi you guys!
Like Kira said, you can take images yourself. They don't have to be of you. They can be of whatever you want. You can even make graphics or photomanipulations as long as the image is good quality.
The site AHubbyof2SexualMinds mentioned works. Free Photos
Another place that's great for free-to-use images is Flickr. They have a Creative Commons area with explanations of the different types of licenses. Flickr Creative Commons
If you guys have any questions about these licenses and what's okay to use on SexIs, drop me a line at rayne[at]edenfantasys[dot]com.
Finally, some people don't mind so much if you use their stuff so long as you give them credit for it. If you see something online that you want to use, and you can determine who the creator is, feel free to contact them and ask them if they're okay with you using their stuff. Just make sure you put their information in the "Copyright" section in the image wizard.