Ooooh, I'm so into doing this for almost all my classes/students now! So real quik if you are in android world (I have a Samsung Galaxy) I'll save you time now : don't bother w/a single of the free apps you'll find on Google Play -- all junk, super limited, frustrating, wastes of MBs... If you are non-iPhoner, then you may also be a pc person, in which case I echo the Movie Maker recommendation above -- decent software for sure, simple design, you can easily become a pro/expert after just like 3 or 4 movies... I've now made dozens of edited movies (finally!) over just the last month or so, and each one is faster / more efficient to edit than the last, I'm just getting so swift w/how to maneuver in the program, & all the options, etc...
That all said, I have to give props to iMovie, bc even tho I'm not a Mac user, about 5+ years ago we borrowed one from a friend just to be able to put together a slide-show movie for an anniversary event... And WOW... First of all, yes I agree that it can be a bit overwhelming, because I think that application offers a LOT of options/features. However, since we were doing something so simple, our friend did a great job of showing us the few steps we had to stick to that were narrowly focused on what we wanted to create. And even then, we quickly caught on to several of the great audio options, and on those alone, even iMovie of 2008 kicks MM of today's butt...
So if u have access to iMovie, I'd say it's worth it to tuff out the learning curve on that one, esp w/the option of having it on your iPhone for free too... Otherwise if u are on a PC, for a novice, Movie Maker will likely more than suffice for what your editing needs/desires are, at least initially, and there's the bonus of it being super user-friendly so you'll ramp up with it fast.
Good luck!