First download the program here: Click here for TS3 Download
Once installed, open the program and click the "Connections" tab. Click "Connect" and then enter the server IP and your name as shown in this screen shot:
Then you're done!
Because not all channels are accessible without membership, make sure you then go to the YGC Home Page, scroll to the bottom and sync your website account with your TeamSpeak. This will give you your member tag so you have permission to enter any channel. (Otherwise you'll have to wait for a mod or admin to assign it to you)