Photoshop and Gimp are both really similar.

You can use Gimp instead of Photoshop and it wouldn't make much difference.

About the Mapping, use the template and preview it.

The preview is made by the following path.

Filters>map>Map Object.

Select the first List to sphere, and look at the tabs options.

You can remove light for a better vision.
Don't forget to merge layers before preview.

So the Job is to do, preview, go back and redo.

Easy.