How is the information stored in a gene used to produce a functional protein?

The genetic code is translated from DNA into messenger RNA, a process known as transcription.
Messenger RNA is leaves the nucleus and enters the cytoplasm.  In the cytoplasm ribosomes attach and the messenger RNA and read the code that it contains.  The code is read in triplets, starting with UAG.  UAG is known as the start codon and codes for the amino acid Methionine.  Each subsequent triplet codon codes for another amino acid.  The process of translating the code from mRNA to an amino acid sequence is known as translation.

The sequence of amino acids (primary structure) determines the shape of the protein (secondary, tertiary and quarternary structures).  A lot of hydrophobic amino acids make a globular protein where the hydrophobic amino acids go to the centre of the protein to stay away from the aqeuous cellular environment.

First of all DNA will converted into mRNA by means of RNA polymerase.This process is called translation

Eventually, this mature mRNA finds its way to a ribosome, where it is translated. In prokaryotic cells, which have no nuclear compartment, the process of transcription and translation may be linked together. In eukaryotic cells, the site of transcription (the cell nucleus) is usually separated from the site of translation (the cytoplasm), so the mRNA must be transported out of the nucleus into the cytoplasm, where it can be bound by ribosomes. The mRNA is read by the ribosome as triplet codons, usually beginning with an AUG, or initiator methionine codon downstream of the ribosome binding site. Complexes of initiation factors and elongation factors bring aminoacylated transfer RNAs (tRNAs) into the ribosome-mRNA complex, matching the codon in the mRNA to the anti-codon in the tRNA, thereby adding the correct amino acid in the sequence encoding the gene. As the amino acids are linked into the growing peptide chain, they begin folding into the correct conformation. This folding continues until the nascent polypeptide chains are released from the ribosome as a mature protein. In some cases the new polypeptide chain requires additional processing to make a mature protein. The correct folding process is quite complex and may require other proteins, called chaperone proteins. Occasionally, proteins themselves can be further spliced; when this happens, the inside "discarded" section is known as an intein.

Information flows from DNA to RNA to protein. In transcription an mRNA copy is made from DNA. Then in translation the RNA is interpreted to produce a protein. Proteins are composed of chains of amino acids. The sequence is determined by the presence of an initiator codon AUG, this marks the reading frame. Every three bases (C,G,A,U) encodes an amino acid). The reading frame ends when a stop codon is reached, signaling the end of the protein.

To keep it short is difficult, its a complex process. Not my fault but it's true. Many parts of it don't make sense unless you explain other stuff. As I wrote this answer, every sentence I started I immediately ran into things that required background explanation. In keeping it short I've had to jettison lots of important stuff and put in some functional inaccuracies you pragmatically shouldn't be too worried about. If your friend wants to really understand it, you can't specify a short explanation. It kills me not to do it justice but here goes.

A protein is made of a chain of amino acids (We have twenty amino acids, each which their own structure). Each amino acid is attached to a tRNA (transfer RNA) molecule floating around the cell.  All these tRNA molecules are the same, except for that depending on which amino acid it is carrying it has a different structure on the opposite end of the molecule. This structure can be represented by a triplet combination of three of four letters: A, C, G or U each of which represents a different molecule. (eg AGC or CCU etc). You had to know that bit. Now, a section of DNA (the gene) is split down the middle (like a ladder cracked in half vertically), leaving the "letters" (bases) exposed. One side of the DNA ladder's bases is transcribed into a strand of RNA (whose only job is as described here).  Determining this is that A-->U, T-->A and C<-->G, acting like a template. Hence if the DNA said AAGCTCATG, the RNA would say UUCGAGUAC. These two strands are called "complimentary" to one another. That part's called "transcription". The next part is called "translation". The strand of RNA encounters one of those tRNA molecules, the amino acids they hold depends on what set of three letters lies on the RNA. This is because of those different structures at the other end of tRNA molecules. They have to be complimentary to the RNA molecule, like a template again. From the RNA strand used above: UUCGAGUAC (ie UUC-GAG-UAC) the first amino acid to meet the RNA is going to be carried on the tRNA molecule that says AAG, because it is complimentary to UUC (in this part A<-->U). The amino acid specific to AAG will break off and form the chain that is the protein. (Technically a polypeptide chain, but a protein for simplicity). The next will come with CUC and join, then AUG and so on. In reality, genes are thousands of triplets long. That?s how we end up with the specific protein from the DNA information, oversimplified.
To put it very basically, using the complimentary system of templates explained above:
DNA-->RNA-->Amino acid chain (protein). The protein then goes off to serve a function, become part of a structure or be useless and break down into it?s individual parts again.

DON'T SUBMIT THIS! I'd be embarassed it's so oversimplified and full of baby language, it doesn't even mention rRNA. I've studied this process in detail for my HSC and the whole thing took four pages to write out (go me I got full marks for it.) I've written this only as to help you better understand the proccess, so you can write it yourself.