The background on the image is created with a scan of old paper I got from Lost and Taken. That was right when I started learning about layer effects in Photoshop (which I now use all the time), so I made the paper blue-ish by adding a layer of light blue with the “Multiply” effect applied to the blue layer.
The colored blots (it’s one layer of blue and one layer of pink (both using the colors I made for my Yves Klein comic (in MadInkBeard No.3))) were made from a photograph of a cloudy sky (I have tons of those). I used the magic wand tool to select parts of the cloudy sky. As I recall, I set it to non-contiguous and then just adjusted the tolerance setting until I got something I liked. The sequencing of the panels is basically an increasing (blue) or decreasing (pink) level of tolerance applied to the same image. Once I had those areas as selections I just filled them with the color I wanted.
The blue layer was then set to “Darken” (which didn’t do much other than toning down the blue a bit), and the pink layer was set to “Screen” which left the pink mostly unchanged where it overlapped the blue layer but changed it to that nice faded out color where it’s just overlapping the paper area.
The comic that follows this one in the issue is basically done the same way except with another colored layer and some slightly different layering of effects.