Go to the settings pane in Contact Form 7, there, select your form.
In the section "Form" you should see your settings for the form. For example, you could have:
<p>Name:<br />
[text* your-name] </p>
<p>mail:<br />
[email* your-email] </p>
<p>Message<br />
[textarea your-message] </p>
The user fills these and sends you a message. Below that, you see the section mail. In the "From" field, change whatever you have in there for [your-name] <[your-email]>, then you should receive the message from: "The Name the User Gave <themailaddress@theuser.gave>.
Hope that helps!