In this very detailed tutorial I will show you how I made a Merry Christmas greeting card with photoshop.

Create a new file (File>New), having 600x800 px and 72 dpi. 

Using the Rectangle Tool (U), try to make the background of the picture we want to represent next.



Apply for the made layer the next parameters by making a click on the same layer on the layers’ panel.
Fill 0%
Blending Options>Gradient Overlay



Gradient’s parameters:

 



Select now the Pen Tool (P) to draw a ray of white color which shape may be corrected with the Convert Point Tool.



Using the same tool and the same method, draw one more ray of white color.



Take the Pen Tool (P) to represent several rays of white color too, as in the picture below:



Getting a better result it’s possible when combining in a group all the layers containing the white rays (press Ctrl button to mark out the corresponding layers and hold on left mouse’s button when taking the marked layers on Create a new group selection). Apply for the made group the following parameters: Opacity 50%



Choosing the Rectangle Tool (U), try to make the primary layer of the pattern’s element:



The layer’s parameters: Blending Options>Gradient Overlay



Gradient’s parameters: