Open iTunes and click on the "iTunes Store" link on the left menu. Look at the upper right corner of the window to see if you are signed in. You must not be signed in to the iTunes store to proceed.
If you see an email address, you are signed in and need to sign out. Click on the name and then click on the "Sign Out" button in the pop-up window that appears.
If the words "Sign In" appear in the upper right corner of the iTunes window, then you are not signed in.
Click on the "App Store" option. This will take you to the home page of the App Store. Purchase any free App by clicking on the "Free" button or the "Get App" button next to the App's icon.
Click the "Create New Account" button in the pop-up window that appears. Click the "Continue" button on the next page.
Read and accept the Terms and Conditions. Check the box labeled "I have read and agree to the iTunes Terms and Conditions." Click the "Continue" button.
Enter the requested information, including email address and password. Click the "Continue" button when you have entered all the required information.
You will be presented with a variety of payment options. Select the radio button marked "None" and then provide your name and address.
The next page will tell you to "Verify Your Account." Click "Done" on this page. An email will be sent to the email address you provided. Open this email message and click on the specified link to activate your account. You will be prompted to sign in to your account.
You will now be able to download any free content available through iTunes, including music and videos.