How evolution works?

Through mutations and natural selection.
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Evolution favors the most adaptive individual. Adaptive ones have always survived and moved their genes ahead through propagation. If some individual of any organism has had an mutation in its genes (which happens time to time by coincidence), and it has had advantage in life because of it, most likely this individual has survived better than the others and could have produced descendants more easily. So the good mutation has spread through descendants during several generations and has became standard feature of that species. At the same time the others with inferior genes have slowly passed away, because they couldn't had so many offsprings than the strong ones. Like this the natural selection favors the strong ones who are most suitable for their living environment.
And through time new species have developed from the same ancestors, when species have moved to another environments and developed new features suitable for their new needs.
This is the evolution from onecelled creature to human:

In process... my drawings, not evolution (or it is actually always in process)

How human became human?

Through evolution.
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Human has evolved from the same ancestors as all the other primates of today, meaning apes and monkeys. Human has not evolved from monkeys, but the same paleo-primates as them. Humans and monkeys ways separated some millions years ago. In the line of the human there have been many other species besides the Homo, which developed to modern human. Some of the species were: Australopithecus Afarensis, Australopithecus Africanus, Paranthropus Aethiopicus, Paranthropus Boisei, Paranthropus Robustus, Homo Habilis (used tools), Homo Ergaster, Homo Erectus (walked on two legs), Homo Heidelbergensis, Homo Neanderthalensis (Neanderthal human) and Homo Sapiens (modern human).
All the other species except Homo Sapiens are dead by now, or in the case of Neanderthals, mixed with modern human. All the non-african people still today have some Neanderthal genes in them. The next relative of the human today is bonobo chimpanzee, smaller version of regular chimpanzee, living in Kongo. The other large primates are gorilla and orangutang. Even human and chimpanzee have 98 percent same genes they are still gone far away from each other during millions of years.
Often there is speak about a "missing link" between humans and apes, but the whole idea of missing link has been wrong from the very start. There is no holes to be filled with missing links in human family tree. It is proven perfectly that humans developed from paleo-primates like the apes aswell.

How the life began?

By coincidence.
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When the Earth was formed (by gravity) and cooled enough, in the primal water started a reaction. It may have started by lightning which constantly thundered proto-earth. Molecules combined and the first cells were created. This happened just by coincidence. The cells evolved and formed some bacteria, first organisms on Earth. Bacteria evolved through time and they started to photosynthesize, to produce oxygen. These were plant cells. First plants were seaweed. Plants moved to land through time and produced more oxygen. Land was full of plants which used carbon dioxide and transformed it into oxygen. At the same time first animals were evolved at the seas. They were invertebrate organisms, kind of worm like. Through time invertabrates evolved to fish, fish to amphibians. At that time there were enough oxygen in the atmosphere so the animals would be able to move to land and breath air. First insects and other invertebrae moved to live on land. Then the amphibians developed lungs, first with gills, later gills removed. They start to breath air aswell and they came ashore first just to lay eggs. Later they moved to live on land. Amphibians evolved to reptiles. Reptiles became dinosaurs, pterosaurs (flying reptiles, not dinosaurs), ichtyosaurs and plesiosaurs (reptiles which lived in seas, not dinosaurs). While some dinosaurs evolved to birds, some reptiles evolved to mammals. Mammals evolved through time and many orders and species were formed. Finally human evolved from the same ancestors as other primates (apes and monkeys).
However human is not the ultimate endpoint of evolution, nor is it the best, most advanced, developed or intelligent species. Humans are just animals like all the others.