The pattern you are looking for is: N-C-C-N-C-C Try finding the backbone in the dipeptide formed from this reaction. In the process, a molecule of water is released and a peptide bond is formed. The carboxyl group of the first amino acid is linked to the amino group of the second incoming amino acid. Peptide bond formation is a condensation reaction. When we write the sequence of a protein, we will always write it from the from "N to C". When looking at a chain of amino acids it is always helpful to first orient yourself by finding this backbone pattern starting from the N terminus to the C terminus. The amino acids are arranged in a single line- there are no branches. Where the first ("alpha") C will always carry the R group and the second will have a double (ketone) bond to oxygen. There are 20 genetically encoded amino acids available to the cell to build in proteins and all of these contain the same core sequence: These will be used to make the peptide bonds between amino acids in a protein (only the amino groups at very beginning (the "N terminus") and the carboxyl group at the very end (the C terminus) will remain in a polypeptide (= protein). The name "amino acid" is derived from the fact that all free amino acids contain both an amino group and carboxylic acid group.
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