What you need:
A phone which can send MMS. (typical phones)
A phone which can send emails. (smart phones)
First, on your phone:
send an email to firstname.lastname@example.org with subject "REGISTER" and also include REGISTER in the email body. You should get a reply saying your device has been registered.
Then, on your computer:
Log into your blogger account. You should be at the dashboard.
For the blog you wish to associate your mobile blog posting with, click on the mobile icon next to the title:
You will then be given a code to email or MMS to email@example.com FROM YOUR MOBILE. Note: it will be different from the one shown below, that's just an example =]
Once you have received a confirmation message, you can now start blogging from your mobile device! Simply send the contents to firstname.lastname@example.org from the registered email or device. It should look something like this:
Subject: [Insert Blog Post Title Here]
[Insert Blog Post Contents in the email body]