I rendered a series of WIPs while creating my latest piece, The Coming of Spring [link]
This is intended to show my process and how I go about doing a photomanipulation. I am assuming that you generally know where things are in Photoshop, but if something is unclear, don't hesitate to ask. I can always add clarification and some screenshots.
This is my first walkthrough! I hope it is helpful. Let me know if there are ways that I can make it more so.
Images used: To my watchers who are new to GIMP:
I checked and you can easily do all of this.
To add a layer mask, go to the Layer menu, masks. Select white for reveal all and black for hide all.
To use the radial gradient: Select the gradient tool (left of pencil). Set opacity around 20%, select the FG to transparent gradient type, select radial shape.
There is no Color Dodge option for the blending mode, but it looks like Dodge should give a similar result.