You will need to define a pattern that you can tile seamlessly across the work document. Some nice patterns can be found here.
Open the pattern file you downloaded and choose Edit > Define Pattern, and close the image. When you wish to use the pattern, select Edit > Fill, choose Pattern from the dropdown, and in Custom Pattern select the image you saved as a pattern. Press OK.
Create a document of size 750×550 pixels and apply your pattern to fill it up.
Right-click on the layer and choose Blending Options. Check on Gradient Overlay and apply the values shown in the diagram