This is a guide to connecting to an external server on Minecraft Pocket Edition. This is not a guide to connecting to a LAN-type world.
Please enjoy, and if I have made any mistakes, please do not hesitate to tell me!
Step 1: Go to Your Home Screen
Begin at your home screen. If you are in another app, simply press the home button, which is located on the bottom of the iPhone.
Step 2: Find Your Minecraft Pocket Edition App
This can be found somewhere on one of you home screen pages or with a spotlight search.
Image credit: Myself and osxdalily.com
Step 3: Open Minecraft
To this by simply tapping on the app. It should come up with a screen like this one.
Step 4: Open Worlds
Tap 'Play' to do this. Next, tap 'Edit', which is in the upper right hand corner.
Step 5: Open External Server
Tap 'External' to do so. This is next to the 'Edit' button.
Step 6: Fill in the Name, Address, and Port.
In this example, I will be opening the Lifeboat 'Survival Games' server. To find a server, search 'Minecraft Pocket Edition Servers' in your web browser. Normally, the website you got it from will have the ip (address) and port. Simply enter these into the slots allotted. It doesn't matter what you call the server in the top box.
For this example, I called Lifeboat SG, and the ip was play.lbsg.net. The port was the default port, 19132.
**A common ip is made up of numbers separated by periods, with a colon at the end, and more numbers after that. The numbers after the colon are the port. Don't get confused, just enter the numbers before the colon as the ip, and numbers after the colon in the Port box.
Step 7: Add and Play!
Tap 'Add Server' when you've entered the name, ip, and port. It will show up on your 'Worlds' screen, ready for you to tap and play!