Genes are a complex set of directions--in the form of chemicals. Genes tell cells, "Do this! Make that!" (Not jobs like "Do your homework" or "Cook some popcorn," though. These are at least partly jobs you decide to do on your own!)
Plant genes give orders like "Grow a flower!" or "Get that bug off me!" Millions of genes work together as a huge but well organized team of natural chemicals to get all of a plant's "work" done at the right time and in the right way.