It takes time to learn MODx, I can easily understand how NewsManager could be hard to understand, but you’ll get there (as we all did !). Maybe one day we’ll find the time to write a tutorial for advanced blogging, but right now, we don’t have it
Anyway, the experience you’ve gained setting up the basic blog will help you reach the next step.
As for adding buttons to the editor, check
Tools > Configuration and at the bottom, you’ve got the RTE editor setting (FCK and TinyMCE). Check the theme : simple, advanced, full... to your liking