final effect
Create a new document (Ctrl+N) and set the document size to 800×600px or 1024×768px according to your monitor resolution. Click the Gradient Tool (Ctrl+G) and select the gradient below in the Gradient Editor.
If you can't see this gradient in the gradient manager, click the triangle symbol to the right of the preset and select Coordinating Color Two in the drop-down menu, and select OK or Add in the dialog box. Find this gradient named Orange, Yellow. Hold down the left mouse button and drag from A to B as shown in the figure below.
The result should look like the picture below
Using the brushes below ( download ), choose a brush set that will add the island you like to your composition.
The one I chose with a brush size of 1223: Create a new layer on top and use the Brush Tool (B) to brush in the middle of the image.
Create a new layer below the island layer. Select the Elliptical Marquee Tool (M) and make a selection of special points where we want to draw a rainbow.
Fill it with color value #12a80d.
