I have read previous threads and they were very useful. I have formed a design from it on paper, but have had to use paint to show you the basics, I'll explain the rest.
The main size is roughly 11ft by 11ft, with two 5ft walls and a 6ft diaganal wall, where I will be putting the door. The walls will be made of standard concrete blocks 7ft high. The thin lines are 2 by 4s common rafters and the thick lines will be 6 by 4s with a 6 inch overhang. The beam going from the tip of the roof to the center of the diagonal wall will be level to give a triangle above the door. I've not yet finished the math to work out sizes, as I wonder if it will work first.
The real question is, have I found the center of gravity? With the corner removed I had to compensate and so moved all beam to the equal distances point. Is it structurally sound or does this now ever compensate?