I'm not sure if there is an easier way but I send them to myself via email, once they are in my email I move them to "My Picture" on the computer and then go into my picture hosting sight and move them from the computer to the hosting sight(I use Image shack). From there I just copy the URL and paste it in the thread. There is a "insert image" icon above the script square in the advanced reply or in the edit square after you've made a post. I usually write the post and them go and insert pictures via the edit function.
It doesn't appear that this forum has image hosting, so you would need to host it on a 3rd party platform like imageshack. (don't use photobucket the a-holes)
from there its just a matter of grabbing the URL and pasting it on here using this button