Fire Background

First, click File>New and set the size at Width 600 and Height 900 pixels.

Assuming you have the Foreground and Background set to the default Black and White colors, select Filter>Render>Clouds.

After this, go again to Filter>Render>Difference Clouds and apply it. If not satisfied with the result, press CTRL+F or CMD+F on Mac to apply it again and again.

Your resulting image should look like in the example here shown:

After finding a suitable filter, select Image>Adjustments>Levels. Move the slider as in the image to add more contrast to the clouds.

After this, select Filter>Distort>Polar Coordinates and select "Polar to Rectangular" in the Polar Coordinates control panel.

Select Image>Rotate Canvas>Flip Canvas Vertical.

Your image should look like this:

Make a new adjustment layer, solid color, as in the example. Let's pick some orange color and click OK. Change the blend mode of the orange layer to Color Burn, 100%.

Make a new adjustment layer, solid color, but this time give it a red color. From the layers box, change the blend mode to screen, 10%. Finally, you can select the background layer and give it a sharpen filter, where you can play with values until you are satisfied with the results.

Your final image should look like this: