Hi and welcome to Librivox!
There are a few things to do before you get started.
You will need to complete a one minute test - this is to check your specs are up to Librivox standards, and if not, you'll be given hints on how to remedy that. http://wiki.librivox.org/index.php/1-Minute_Test
Please post your test in the Listeners Wanted forum (see the dropdown at the bottom of the page) for the speediest response. Waiting for the OK may seem tedious, but can save time in the long run.
You will also need to be added to the catalog of readers. We can also link to a personal blog or website. If you click on your name in the Magic Window, you will see your own personal catalog page.
Be sure to read the first post - all the info you need is there, but if anything doesn't make sense, just ask. The wiki (see the top of the page) has bundles of info too.