start with www.blogger.com
There, you can sign up and just write away. It's really, really simple. You can also try wordpress. I like both.
Then, come back and leave us a link to your blog so we can follow :)
I agree with Happy Mommy! I started about a month ago on Blogger, and since then things have only went uphill. Feel free to visit me at Busy, Young, Single Momma Sanity , and leave a link once you have started:)