When I need to rotate an object I make sure the object is on it's own layer in Photoshop. If it is on it's own layer, you shouldn't need the lasso, highlighting it with a square should do. Right click, choose transform. Then, and I can't remember because I don't have photoshop on this computer, buuuut... hold either ctrl or shift and you should be able to rotate it that way. When you have it how you want, just hit enter. You should be good to go!