How to redeem codes on iPhone 5?

I have an iPhone 5s and I got some codes for an app(fallout shelter)that I just got but i don't know how to redeem them. It says online that IIm supposed to go to the App Store and redeem it but I don't see any button or tab that says "Redeem Code".

How to get downloaded music onto iPhone from iTunes library?

So I've downloaded ace hood s mixtape from datpiff.com and I extract the files and dragged it to the iTunes library. But the problem is that when I click on the MP3 file and try to add it to my phone it shows the song but with a empty circle next to it and it won't download. So if anybody could help me with this I would appreciate it.

Seller on Craigslist wants to ship product?

I found an iphone wanted to buy off of the seller which was a local listing. After I contacted the seller he said he had moved to another state and would have to ship the phone to me. He wants to go through PayPal but I'm not sure if I should forget about it or if its safe.

How to unlock a iPhone 6 plus with a lycamobile sim for free?

I have a iPhone 6 plus and I stopped using it so I told apple to lock it. Now I need it again and it is not allowing me to use a sim. It keeps saying no service. I can access all the apps and such but i can't make calls and use cellular data. I understand that i might have to pay, but is there any other way to unlock my phone for free?

My iPhone flash isn't working?

One day it worked, and the next it doesn't. What happens is, I'll turn the flash on to use it as a flashlight and it stays on for about 4 seconds then automatically turns off. Then, if I'm taking a picture, it goes off, then turns off right before the photo shutter goes off, so the picture comes out black. With a video, it goes for about 4 seconds again then shuts off. It's really frustrating. What's going on?