All iTouches have a photo application when you first take it out of the box. I dont know what kind of iPod Touch you have, but maybe it got messed up. Try restoring it on iTunes, and then sync all your music, apps, videos, and photos back on. However, the photos application should have already been on the iTouch as a default.
To put pictures on your iTouch, you can either take a screenshot (answered in your other question), or you can save pictures from your computer onto iTunes. Then, sync with the iTouch