Step 1: Getting Mumble

You can download mumble from their official website here. (Please do not confuse this with the third party website

Step 2: Installing mumble

That should be pretty straight forward and is heavily dependant on your platform.

Step 3: Configuring your audio

Before you start, make sure that the volume of your microphone is not set all the way in the control panel of your operating system.
In the picture below you can see how to do this on windows 7.

Open properties on your audio input and turn up the mic boost and volume.

Now, go back your mumble, the first time your run mumble you will see the "Audio Tuning Wizard".
If this does not start you can go to the Configure menu and open Audio Wizard.

Now follow this wizard carefully to configure your audio.

Step 4: Certificates

All communications in mumble are encrypted with certificates, a certificate is basically a digital autograph that you can encrypt things with.
Mumble needs a certificate to be able to connect to a server.
As we use password based authentication simply Automatic certificate creation will suffice.

Step 5: Server list

There are a lot of mumble servers out there, some of them are registered on the Public Internet server list.
But to save you the hassle of looking through all these servers, you should just minimize the Public Internet list and click on Add New....
Now just enter some nice name in the Label field, enter into the Address field and enter an username ito the Username field.
It should now look similar to the screenshot below.

Now select the server and click on Connect.

Note: You cannot connect with an username that is registered on the server without knowing the password.

Step 6: Push to talk peasants

To setup push to talk, go to Configure and then Settings.
On the Audio Input tab change the Transmit option under Transmission from Voice Activity into Push to Talk.
Don't forget to also set a Push-to-Talk shortcut on the Shortcuts tab.