How does your body know what order the amino acids should be in to produce a particular protein?

Each tRNA molecule has a specific anticodon (nucleotide triplet) at one end and a corresponding amino acid at the other.

These anticodons are complementary to the codons that are carried by the mRNA transcript.

The tRNA fits into the binding sites of the Ribosome where the translation is happening.

As the mRNA transcript is being 'read', the correct tRNA molecule that corresponds to the codon, adds the the amino acid that it's carrying to a growing polypeptide chain.