This spider is quite small, only about 1/4 inch (6mm) leg span. It builds a flat sheet web suspended between branches or flowers about a foot off the ground, with a tangled network of threads over it. The spider sits on the underside of the web, waiting for prey. I'm not sure what kind it is; possibly in the family Linyphiidae. There are many such small, colorful spiders in the northern hemisphere that go unnoticed if you aren't looking for them.