You can think of genes as information in a computer - they are a bit like files. You might take an image file in permanent storage on a CD-ROM, transfer it to active memory on your computer, and finally print out that image using your printer.
Genetic information works in the same way.
Proteins do most of the work in your body. DNA stores this information in a particular way - DNA information is stored as two intertwining strands. The information on one strand can be used to determine the information on the other, and in fact this is how DNA information is copied. The reasons for pairing are chemical, but you can think of it as due to the shapes of the bases. This has a very important result - If you know the letter code of one DNA strand, you can always figure out the complementary code on the other strand.