A useful creative workspace
GIMP is a cross-platform image editor for tasks including retouching, compositing and graphic work. Choose it when you want control over an image rather than only a fast preset. Its project documentation is a useful companion when a tool behaves differently from another editor you know.
Separate project and export
Keep an editable project as well as the image you export for sharing. The project preserves the structure you may want to revise, while an exported JPEG or PNG serves another purpose. Work on a copy when experimenting with a photograph you cannot replace.
Begin with a small workflow
Try opening an image, making a modest adjustment, adding a layer and exporting a result. Compare the output at its intended display size. Download from the official project and check the current supported-system information rather than following a random plugin bundle.