The first thing anyone interested in voiceover (v/o) work needs is a demo, which is a collection of voice samples. You can listen to a few of my voice samples by clicking on them in the right column.
It doesn’t matter if you’ve never recorded anything that’s actually aired. Just get a script from somewhere and record small bits of it. One easy way to get a script is to watch TV commercials you like and type up the script. Once you have a script, record small bits of it—10 to 15 seconds for each commercial or voiceover script. Record 6 to 10 of those, for a total of 1:30 or so. Put music behind some, if you can mix (see below) and try for a variety of content and style. The whole should show the range of your voice ability. I recommend using STEREO BG MUSIC, NOT MONO (even though voice audio may be mono), because it gives a bigger presence to your demo overall.
Audacity is a good recording/editing program that is a free download from the Internet onto your computer With a decent microphone, you can record your voice, mix it with music you’ve imported, and edit it together for a decent demo that you can save as an MP3 file for emailing or burn to CD. Not terribly hi-tech and fairly easy to learn. It’s what I use for simple recording and edits. For anything complex, I go to a professional studio.