In one sentence, describe what the following article is about:

You can go directly to this page by visiting netflix.com/YourAccount.  Even if you don't use Netflix on your computer, you'll need to visit the web page to make changes to your account. You cannot change your Netflix plan information from the streaming device or video game console. If you pay for Netflix using your iTunes account, see the next section. You'll need to be logged in with your primary Netflix profile to make changes to the plan. This will display the plan that you currently have for Netflix. In most regions, you can select between three streaming plans: One Screen in Standard Definition (SD), Two Screens in High Definition (HD), and Four Screens with HD and Ultra HD (UHD). Each plan costs a little more than the previous one, but allows more people to watch on different screens at the same time.  Netflix recommends a 3.0 Mbps connection for SD content, a 5.0 Mbps connection for HD content, and a 25 Mbps connection for UHD content.  Not all options are available in all regions. This will set your account to use the new plan. The changes you make will take effect at the start of your next billing cycle, but you should be able to access your new features immediately. If you live in the United States, you can sign up for the Netflix DVD rental service as well as the Streaming service. This is handled by a different branch of Netflix. It is not available to customers outside of the US.  Click the "Add DVD plan" link to view the available DVD plans. You will be taken to the DVD plan website. Select the plan that you want to add. After adding your plan, you'll be able to start getting your DVDs delivered.

Summary:
Sign into the Netflix "My Account" page on your computer. Click the Profile button in the upper-right corner and select your primary profile. Find the "Plan Details" section. Click "Change Plan" next to your current streaming plan to see the other options. Select the plan you want and click "Continue." Add or change a DVD plan (US only).