The next screen that appears is a textbox containing the Windows 7 Software License.
Read through the agreement, check the I accept the license terms checkbox under the agreement text and then click Next to confirm that you agree with the terms.
Note: You should always read "small print" especially when it comes to operating systems and other software. Most programs, Windows 7 included, have legally binding limits on how many computers the application can be installed on, among other limitations.
Important: You are not breaking any laws or contracts by reinstalling Windows 7 via this clean install. As long as this particular copy of Windows 7 is only being operated on one computer, you're OK.