If you go to Devices in the left hand pane and select your Ipod, then along the top of that section are headings Summary, Music etc... go across to Photos and that's how you add them!
As njeo said and just select which folder full of photos you want to use on the iPod. I personally didn't want all of mine on, so I just selected a few I wanted on the iPod and set up a new folder for them in My Pictures and pointed the iPod/iTunes towards that folder.