Carbon, nitrogen, hydrogen, oxygen and sulfur.
http://www.biochem.ucl.ac.uk/bsm/dbbrowser/c32/aastruct.html
How are they sequentially put together?
When a DNA open reading frame (a gene) is transcribed by RNA polymerase (a protein) into a messenger RNA (mRNA) it is taken to a ribosome where each three letter nucleic acid ‘codon’ is paired up with a transfer RNA (tRNA) that carries with it the appropriate amino acid that corresponds to that triplet code (the Universal Genetic Code). Thus a sequence of DNA is used as a template for mRNA that is then translated into an amino acid sequence.
Some of the more advanced proteins need other proteins to make sure they fold into the proper 3-D structure. Other proteins fold ‘naturally’; the gist being that there is nothing ‘magical’ about it, it is all electromagnetic interaction. A proper sequence of amino acids in the proper structure is capable of a specific enzymatic, signaling, or structural function.
And with a handwave and a "don't look behind that curtain", the word "proper" dismisses the complexity of the INFORMATION contained in the sequencing.