如何在Mac Pro上以管理员身份运行终端

I am using a Mac for the first time and need to run Terminal as an admin. I have installed NodeJs and Git and want to download Phone Gap/Corova but when I try to install Cordova, it comes back with an error saying I should be an admin when running the terminal. How do I open a command prompt in terminal as an admin to the Mac Pro?I am using a Mac for the first time and need to