To navigate different layers in GIMP, open the Layers panel by going to Windows > Dockable Dialogs > Layers. You can select, hide, or delete layers by clicking on them in the panel. Use the eye icon to toggle visibility, and drag layers to rearrange their order. To adjust a layer's properties, right-click on the layer for additional options like opacity and blending modes.
Press control + L to open the Layers window.
Click on windows / dockable dialogs / layers channels paths
In the "Layers, Channels, etc" window, right click on a layer and click delete.
There's a specific command for that under 'layers'. You can also do it in the layers "toolbox" (wrong term- but the stuff on the right side of the screen)
Press Control + L to re-open the Layers window
IF your picture has multiple layers (it may not - jpeg's don't when brought in) it will allow you to determine which layer is being modified by the editor, and to rearrange which layers are on top.
In GIMP, to draw on multiple layers simultaneously, you can use the "Paint on All Layers" option. First, select the layer you want to draw on, then go to the "Tool Options" for your brush or pencil tool and check the "Paint on All Layers" box. This allows you to apply your strokes to all visible layers at once. Remember to ensure that the layers you want to affect are visible and not locked.
In GIMP, there is no strict limit on the number of layers you can have in a single project, but the practical limit is determined by your computer's hardware and memory capacity. Each layer consumes system resources, so performance may degrade with a very high number of layers. Generally, most users find that they can comfortably work with dozens to hundreds of layers, depending on the complexity of the images and the capabilities of their system.
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To superimpose pictures in GIMP, open both images in separate layers, adjust the opacity of the top layer to see both images, and use the Move Tool to position and align them as desired.
Unfortunately, the only formats that preserve layers in GIMP is .xcf (the default format.) If you're looking to upload an image online, or use the image for anything outside of GIMP, you have to export the file by clicking File>>>Save As>>>(specify format in drop box)
The dialogs in GIMP are windows that contain tools and options that you can use to change your image. All dialogs can be found by going to windows > dockable dialogs. The layers dialog, for example, allows you to view all of the layers in one box and enables you to change the mode and capacity of each layer, along with other options.