If you don't know anything about TeamSpeak, this brief guide may help get you started on your journey to VOIP bliss.
Click here to download a copy of TeamSpeak. Double click on teamspeak2.exe and install it where ever you like to install things.
Double click on the TS icon to run TeamSpeak. Click on Settings, then Sound Input/Output Settings. Set the Voice Activiation Level so that TeamSpeak picks up your voice at a normal speaking level.
Click on Connection then Quick Connect. Fill in the appropriate Server information and click Connect.