This tutorial describes how to create an animated GIF in the free alternative to photoshop: GIMP.
Check out https://www.instructables.com/id/Model-a-3D-Jack-O-Lantern-in-CREO/ for instructions how to design a 3D-Jack-O-Lantern in CREO.
1. Open the rendered image in Gimp.
2. Select the bottom half of the image, create a new empty layer and go to Filters --> Render --> Clouds --> Fog, use a grayish color.
3. Duplicate the new layer for denser fog.
4. Create a new empty layer and go to Filters Render Clouds solid noise. Bring down the layer opacity until the pumpkin is visible again.
5. Go back to the first layer and select the holes in the pumpkin with the fuzzy select tool. Use `add to current selection mode` to select multiple holes. Copy this selection to a new layer and fill with a light-yellow color.
6. Add another empty layer and use the paintbrush tool to add light effect. Now you have to group the layers into two groups: one pumpkin without light emitting and one pumpkin with light emitting. Export both to a jpeg file.
7. Create a new image, paste the two jpeg’s and duplicate the layer without light emitting a number of times, as every layer will become an animation frame. Finally Export to GIF. Make sure to select “as animation”.