There are many ways/tools. The exposure slider is one, 'though it's sort of a 'sledghammer' approach. I prefer to do exposure correction in Lightroom, and apply the changes to the raw file using the highlights, whites, blacks and shadow sliders as well as the curves adjustment tool to get exactly the level of exposure I want across the image. If I'm doing any corrections in Photoshop, then I tend to use Levels or Curves adjustment layers.