Ok, start with creating a new document sized 500×500 pixels and use the Paint Bucket Tool to fill canvas area with color of #355b00. After that create a new layer and apply the Elliptical Marquee Tool to make a sphere selection as on a picture below, then fill this selected area with color of #97f501 Remove selection with pressing Ctrl+D and for the image jitter apply Filter > Blur > Gaussian Blur
![Make a Collage Using Mosaic Effect | Photoshop Star](https://cdn-ak-scissors.b.st-hatena.com/image/square/2bf19781606d17c1051a6453ecb177da41c0b2d7/height=288;version=1;width=512/https%3A%2F%2Fphotoshopstar.com%2Fmedia%2F2009%2F11%2Fcollage_01.jpg)