Join Mumble (Info is mumble.serinus.us port 7260 if you prefer to type it yourself.)
This is just your browser asking you if it's okay to launch mumble. Hit Allow.
Enter your name and server
Hit Yes. This warns you that noone else has verified this is my server.
Use Push to Talk and set a key
We want to look at the quality settings in more detail
Set your quality all the way up. We pay for it, go ahead and use it.
Choose if you want the overlay to display
This will make the display more similar to ventrilo.