How to do that on the iPhone 5?

Like putting a song so that when someone is calling u, they listen to it?

You need to make a ringtone on itunes and import it to your phone, and then go to the contact and pick the ringtone. If you don't know how to make one, youtube it

That's called a ringback tone, not a ring tone (ringback tone is what the caller hears before you pick up, the ringtone is what YOU hear when they're calling).

Anyway, ringback tones are created by your carrier (phone company), not your phone - since they need to work even if your phone is turned off.

So if you can do them at all, it's a service from your phone company, not something you set up on your phone. And that means it doesn't matter what kind of phone you have, instead it matters which phone company you have.

They don't have that anymore:/