This is a process called transcription and translation.
Information to synthesize a particular protein is found in DNA in the cell nucleus. This information is copied (transcribed) onto messenger RNA or mRNA in short. The copying process is called transcription.
mRNA then leaves the nucleus and enters the cytoplasm where it attaches to a ribosome. Transfer RNA or tRNA then begins to read (translate) the information on the attached mRNA. This is the process of translation.
tRNA then fetches amino acids that correspond to this information and brings them to the ribosome where they are linked together into a chain. This chain of amino acids is the primary structure of the protein.