There is no need to "save" your image. Whatever adjustments you made are always there, but you can step back in history, or reset to the original (pre adjustments) if desired.
You can export if you want to product a copy in a different format ie jpg, or resolution etc.
|Valley by the light of a blue moon by cjf2|
from Down in the Valley
|Lake Erie Stone Pier by yobbyt|
from Dock or Pier