Open Minecraft: Pocket Edition
Log in to your POCKET EDITION realms account. If you don't have one, create one.
When you get to this screen, press "Edit" in the upper right.
Once you pressed "Edit", your screen will look like this. Press "External".
The screen will look like this. Now, open safari, or another web browsing app.
Type in, "MCPE servers; Minecraft PE servers; Minecraft pocket edition servers" ETC. I recommend this website to find good servers.
Click on a public server that interests you. If you are on this website, something like this should pop up.
Copy the address into Minecraft (iOS 7's multitasking makes this easier, because you can't copy and paste :3)
The port may be the same as the default, but if one or two numbers are different, change them.
Name the server whatever you want, then you are done! (WARNING! Some servers are sometimes full or busy, so you may not have the ability to go on them all the time) Other than that, have fun! :3