This is a really hard one to answer (and for once, you'll probably not get much help here).
Proteins are long-chain compounds of carbon, oxygen, hydrogen and (crucially) nitrogen. They can be considered to be formed by linking LOTS of "bits" of amino acids together. (Amino acids are traditionally referred to as the "building blocks of life" - which is a bit like saying that the silica in sand is used to make a house - not actually wrong, just misleading). So far as we know, proteins are ONLY made by living organisms and there are many of them, each with a different function to perform. There is, as you might imagine, a lot more to proteins. The wiki page is a bit "stiff" and less than easy to understand. There is useful (and easier to understand) information in Bill Bryson's book - "A short history of nearly everything" - which every library in the English-speaking world should have a copy of.
