1. Create a new document (Ctrl+N): Width = 400, Height = 400.
  2. Now, Filter > Render > Clouds.
  3. Now, Filter > Render > Lighting:

    Settings

    Light Type: Omni
    Intensity: 35
    Gloss: 100
    Material: 100
    Exposure: 46
    Ambience: 17
    Texture channel: red

    Now for the two colors that you see there:
    The first one(top) make it orange.
    The second one(bottom) make it red.
    For a flame effect go to Filter > Brush Strokes > Accented Edges and play around with the settings.

Fire effect final