How to i get the words " Enter Your Email " to appear inside the email field?

Hi
How can i get the words " Enter Your Email " to appear inside the email form field?

Here is my site you can see I don't have it inside http://goo.gl/k9mJG

This is what we are trying to have it look like http://postimage.org/image/bkqvm1zev/

This is how i want it to function. When a person sees the field they see the words " Enter Your Email" and then when they click in the field and begin to type their email those words would disappear. But if they removed their email the words " Enter Your Email " would reappear