I framed my walls with 2×4s laid 24” O.C. There will be a window on the left and right wall that I got for free from work, and then there will be a 36” steel door in the front. All walls came out square and plumb. I am glad that I designed it on Google SketchUp first because I ended up having just enough lumber as planed.
Thanks for looking. Now I have to get material for siding and the roof.