In the CSS style for the body element you can specify a background-image property with the URL to the image:
background-image: url(stars.gif);

The background attribute in the HTML body tag is deprecated. If you specify a background image, you should also specify text, link, and background colors since the reader's default colors may not provide adequate contrast against your background image. The background color may be used by those not using your background image.

This is substance produced by plants or animals, or a synthetic analogue thereof, that evokes a behavioral response in individuals of the producing species or other species (e.g. allomones, kairomones, pheromones, and synomones).

Its chlorophyll..
Chlorophyll and sunlight are the source of all the food ...and primary component of food chain...

Food biotechnology is a process scientists use to enhance the production, nutritional value, safety, and taste of foods. It can also benefit the environment by improving crops so that they need fewer pesticides.

GM products, and GM plants in particular, will have a positive impact on the environment by reducing agricultural chemical use and by promoting good agricultural practices such as no-till agriculture.
These crops could effect the environment through
1) transfer of the GM traits to other plants
2) harm to non-target species
3) increased resistance to commonly used insecticides and herbicides

GMO - Genetically modified organism (GMO) is Genetic material of an organism is  altered with the help of genetic engineering techniques generally known as recombinant DNA technology. DNA molecules from one source is combined with the DNA of other in vitro into one molecule to create a new gene. The recombinant DNA is then transferred into an organism causing the expression of modified or novel traits. The product is also known as an Genetically Engineered Organism or GEO.

Examples Transgenic animals (mice, fish),  transgenic plants (BT Cotton, Flavour Savour Tomato), or various microbes (fungi and bacteria) . The production and use of GMOs are ivolved in biology or medicine, for the production of pharmaceuticals and industrial enzymes, and for direct, and often controversial, applications aimed at improving human health (e.g., gene therapy) or agriculture (e.g., golden rice). For example, a gene from a jellyfish, encoding a fluorescent protein called GFP, can be physically linked and thus co-expressed with mammalian genes to identify the location of the protein encoded by the GFP-tagged gene in the mammalian cell. The indispensable use of GMO is in many areas of research, such as to study the mechanisms of human and other diseases .