The first thing you need to do is acquire an e-mail program (Windows 7 does not come with one). There are many choices, some by Microsoft, some by third parties; some free, some free, some for sale. Do web search to find out what the choices are and which one you might want.
I'll also mention that another choice is using a webmail service such as gmail instead of an e-mail program. Webmail has become very popular lately but as far as I'm concerned, it's a terrible choice. In my view, the worst e-mail program is a better choice than the best webmail. I strongly recommend against webmail.