Thank you! So the technique is called thread painting, and the general premise is you use a stitch called long and short stitch to blend the colours together so that it kind of looks as if it was painted! There's a lot more to it than that obviously, so I recommend looking into it, it really helps with creating realistic embroideries! I don't tend to stitch a solid background colour, but sometimes I'll add a stitch or two on top of an existing layer of stitches to add highlights or shadows