Poster Troubles!

I have finally figured out how I want my poster. The main thing on it is the sketch of the treehouse from google sketchup placed in the tree (it is almost like the background). The only thing is i am running into the issue of placing the other sketches that i actually drew on the poster. they keep looking out of place. I am in the process of fixing it or trying to maybe i will make a bigger grid and see if that helps.