After the installation completes, you may wish to visit the settings for the plugin.
To set all the blogs on the system to the same value, change the settings at the system level. Most of your settings will be picked up and you can then tweak your settings at the blog level for any exceptions.
This makes management much simpler.
Once set at the blog level, the system level settings may be reapplied at any time by selecting to reset the settings. By doing this, however, your changes will be lost.
For detail on any configuration setting, see the appropriate item.
After you've gone through the settings, take a look at your comment template, because it's where most of the action takes place. In there, you will probably want to check out the comment integration so that you can see what happens and how to make sure you have everything set up correctly for MT-Approval.
You might also want to at least glance over the challenge integration if you would like to add another - or different - layer of comment security to your commenting process.
Finally, head over to the template tag reference to put MT-Approval to work in earnest and really stir up the pot with your own concoctions.