You may get .psd* file of "Unusual Christmas Card" Photoshop tutorial by making a payment. Put the tutorial title in "Add special instructions to seller" line of PayPal and it will be sent to you shortly.
- Create big white spot in a new layer, apply Dissolve Blending Mode, Opacity 6%.
- Merge it with a new empty layer.
- Apply Gaussian Blur Filter(1).
- Create big white spot again.
- Apply Dissolve Blending Mode, Opacity 6%.
- Add layer Mask, fill it with Radial black and white gradient just like on the screen shot.
- In final, merge all layers.
- Click on Quick Mask Mode icon
- Choose Gradient Tool. Fill work with Reflected black and white gradient.
- Click on quick mask again, keep selection.
- Go to Filter > Blur > Lens Blur.
And here is result. Click for larger view!