How to set up mumble
First download mumble from here
http://sourceforge.net/projects/mumble/files/
Then follow the steps are they are explained and picturized:
Step 1:
Open mumble and click on CONNECT
Step 2:
Click on ADD NEW
Enter the following details:
Enter a username that you want to use and keep
Click on OK
Click on connect
Step 3:
Right click on your name and choose for REGISTER.
On the warning that pops up, click on YES