Fire in Paint.NET

This is how to create fire with Paint.Net

First open a new document and create a new gradient like this

Then add a new layer and set it's blending mode to overlay(double click on layer for layer properties). Then add the effect "clouds" to this new layer. Repeat the process(Ctrl+f) until you think it has a good shape.

Now flatten the image. Then under the adjustments window select "curves". This is a bit tricky, select RGB in the drop-down-menu. After that tick off only the blue box at the bottom and move it to the right. Then the green and move it between the red and blue. They should look like this.

Anyway once that's done you've got one good looking flame effect.