Book of GIMP : A Complete Guide to Nearly Everything by 
The Artist's Guide to GIMP by 
Photoshop for Right-Brainers by Software Needed: GNU Image Manipulation Program (GIMP)
Images: Available here.
Before beginning your photo manipulation, take a few minutes to look over the software. Make sure the Toolbox - Tool Options and Layers - Gradients Docks are open. This can be found on the Windows drop down menu.
Steps
Open up all the provided images that will be used for this photo manipulation. The base image that we will be working on is of a forest at night.
Navigate to the image of the person wearing makeup. Select the Lasso tool and select around the outline of the person’s body. Copy (CTRL C) and Paste (CTRL V) this into the image of the forest.
Using the Move tool and the Scale tool, move the person around until you are happy with the size. Use the Lasso tool and Eraser to remove any white space near the hand, around the head and the ears as well.
Right click on the Floating Selection (Pasted Layer) in the Layers - Gradient Dock and select To New Layer.
Use the Lasso tool to select the face of the person. Make sure the Feathered Edges Checkbox is selected and set the radius to 20. Use the Eraser tool to erase the selected face.
Move to the image of the cat. Repeat Steps 2 - 4 on the cat ears and eyes, adding them to the image manipulation.
Using the Eraser and Rotate tools, clean up the unusable parts of the ear and situate them how you would like on the person's head. Do the same for the eyes.
Click all the Eye Icons in the Layers- Gradients Dock except for the person and cat ears. Right click and select Merge visible layers. The selected layers are now one layer. Select the area where the Eye Icon was to turn the invisible layers back on.
Make sure the Person layer is selected. Select the Color drop down menu and select Color balance. Adjust the Cyan, Magenta and Yellow color levels until you feel it matches up with the background lighting.
Select the eye layer. Repeat step 9 to change the color to whatever you prefer.
Navigate to the galaxy image and select the Select drop down menu and then All. Paste this into our photo manipulation and repeat step 4.
Drag the galaxy layer down beneath the person layer. Change the Opacity of the layer to around 70%. Take the Eraser tool and remove any section to the space layer that you would like.
Select the butterfly wings and move them to the image manipulation one at a time. Using the Scale and Rotate tool, add them as accents around the face. Combine the two layers like in step 8 and change the opacity to around 40%.
With the butterfly wing layer selected, open the Color drop down menu and select Hue-Chroma. Play with the Hue, Chroma and Lightness settings until you find something you like.
Navigate to the image of a bird. Follow steps 2 and 4 again to add it to the image manipulation.
Right click the bird wing layer and select Duplicate layer. Select one layer and Rotate and move the wing until it covers the person’s shoulder. For the other layer, select the Flip tool and flip the wing for the other side. Then Rotate it to mirror the other wing.
Lower the Opacity of the left wing to erase sections where the person's hand is covered.
Combine the wing layers just as we did in step 8. Once the layers are all visible again, make sure the bird wing layer is selected. Select the Color drop down menu and select Hue-Chroma again. Mess with the Hue, Chroma and Lightness settings until you find something you think matches the image well.
Congrats! You’ve just made your first photo manipulation!