Stl help needed outside edge is rough on a circular object

Can someone help me with a stl file.I made a circular mount the best i could,its almost finished but the outside of the ring has some indensions that need to be made flat to match the rest of the outside/contour .Im new to modeling so forgive my wording.Any help with this would be greatly appreciated :slight_smile:

Its not clear what you are asking for.

The object is round,it has a channel on the outside and a few indents and i want it flat like the rest of the model