I'm not so experienced with the bitcoin-qt client (assuming this is the client you're using, as it's the 'default' client).

But I think the address book is for existing addresses that you don't want to memorize in your head (like a telephone book where all of your contact info of your friends and family are stored).

You can't really specify how your own public address will look like (unless you want a vanity address, but it requires lots of computing power to generate one), but if I'm not mistaken you can create a new address by going to the 'Receive coins' tab and hit New Address.