I couldn't find the tree either .. If you look at the row of icons on your Quick Reply box you will see a yellow smiley face. Then 2 blue spheres (one with a red X ) Then a square box with something in it. That something is the tree.
I haven't used that one but if you go below the quick reply box there is a blue strip that says "Go Advanced" There is a way to load pictures there. That's what I use. But be sure to reduce the size of the pictures or they won't load.
Hope this helps.