1 post is nowhere near enough. Reply to or start your own threads. I'm not sure how many posts are required to create an article (hopefully a Mod will chime in on this) Once you have the required number, click on the Coops button above, scroll down a bit until you see another button labeled "Add Your Coop - Click Here". Hit that and it will take you to the tutorial page telling you all you need as well as providing links to the creation page (If you already know how to write an article, the "Add A Chicken Coop Design" button is a little lower on the coop page).
There are no branches that protrude into the run or coop, but they do have a few that I put in there separately. It's nice, because the tree shades them in the summer, and blocks the wind in the winter. They seem happy. Heck, they are birds, figured why not put them in a tree