First, pick your color (on the right hand side) while the grid loads. Next (once the grid is generated) type in the number of pixels you want. The more pixels, the longer it will take to make. Finally, wait for the pixels to generate, and now you have a randomly generated set of pixels. After about 30 pixels, It starts to slow down.
Shout out to Ingoguy15 for one of his projects which helped me on the grid code. Not really the best generator, but hey, at least I tried.