I use an outside source like Photobucket. One that has the image code. I copy and paste that into the thread and it posts it.
example (with spaces so you can see the code) [ IMG ]http://i4.photobucket.com/albums/y105/S2_Rp/Photoshop/BlackHoleAssasin.png[/ IMG]
If you are trying to load it through Ninjette you have to use the Advanced reply (not quick) photo upload which is the little button that looks like a paperclip. Browse for the image on your harddrive and embed it for you.
Hope that helps!