Quick Correction of Dark Photo in Paint Shop
Open the photo.
If the layer palette is not visible, display it by right-clicking on any toolbar and selecting it from the menu (Palettes>Layers).
Right click the background layer, and choose duplicate.
The blend mode for the duplicate layer will be Normal, click the arrow next to Normal and change the blend mode to Screen.
If the results are too light, lower the opacity slider next to the blend mode menu in the layers palette.
If the photo is still too dark, right click the screened layer and duplicate it again. Adjust opacity as needed.