Create a file of your desired dimension. We are taking 1280px width and 960px height. Select transparent background.
Select the file through Marquee Tool.
Add gradient. We are creating a blue sky look, select the gradient tool, click on the gradient color select tool.
Select the colors (from light to darker blue shade). Apply the gradient effect to the selected area.
Bottom half of the file is to be used for garden selection. Create a new layer, select an area through Polygonal lasso tool and apply gradient (same as in step 3).
Now add object in your file. You can add images, however if you are interested if creating your own images, you can do that. We start with a tree, create a new layer. Select a desired area through Lasso tool.
Add Effect, go to blending option and select Bevel and Emboss.
Add Bark of the tree the same way. Make a copy and place them as per your need.
Fill your file with relevant images.
You can add images. Source