Since iOS 8 Apple included an open in and share extension which makes life so much easier, this guide shows you how to add extensions.
To access your Share extensions, tap the Share button in any app. (The rectangle with an up arrow coming out of it.) For this example, you can tap the Share button in Safari to share the current page to another app.
In the top menu — the one that begins with Message, Mail, Twitter, and Facebook — scroll to the right side and tap the More button and you will see a list of installed Share extensions. Enable the extensions you want to use, and disable the ones you don’t want to use.
You can also re-order this list by holding the handles and moving them up and down.
When you’re finished tap Done and the Share menu will now show your favorite services and remember your preference.