You can browse our guide to install iOS 11, which released beta version. In a few steps, we will explain how to install iOS 11.
To install iOS 11;
First, back up your device to the computer. Because you probably won't be satisfied with iOS 11. You should take your backup to get back to iOS 10 right away.
If your backup is complete, click this link and create your profile as a developer.
After this process, check your update. iOS 11 beta update will be downloadable for you.