How to add a video intro to a video clip?

Details here.

So, I have a youtube channel, named Clash Raider.
I make videos daily about Clash of Clans, and it's taken through a screen recorder for my iphone 5s.
I can upload them to youtube fine, but I wanted to add a video intro to it, so it looks better.
(Those intros that have the channel name, before the video)
So I made an intro on window's movie maker, and it plays perfectly fine, but I don't know how to merge the two videos together! (I have a video from my iPhone recorded already).

I tried to add the iPhone video to the movie maker project, BUT, it only has audio and the video only shows up as a black screen!

The intro works fine, then it goes to an audio with black screen!

So is there any other way to add the intro/recording together?

You need a simple video editor. You add the intro then add the movie. Done. Go to the app store and look for an editor.

In the comuter, convert the iPhone video to a format MovieMaker can deal with - Handbrake from www.handbrake.fr can do that - then add the iPhone video to the intro and render/save as/share the project to a YouTube friendly format and file type (MP4, AVI, WMV).

Higher quality = lower compression = larger file size
or
Lower quality = more compression = smaller file size