Mic recommendations for Sony a5100?

Hello everyone.

This is my first post on this forum. I am a complete newbie to cameras. I mean like completely new... to the point where I just found out yesterday that there's a difference between a camcorder and DSLR. 

Anyways, forgive me for the newb question, but I wanted to start making YouTube videos, and found a Sony a5100 that my wife bought for our wedding pictures a couple years ago. I want to start filming myself in my office talking to the camera no more than 10 minutes per video. Correct me if I am wrong, but I am assuming that the mic in the camera will pick up a little bit too much static and it would be better to purchase a mic for higher quality videos. Upon inspecting the camera, I don't see a mic input, so I am assuming I have to buy a separate mic/recorder and then use video editing software to overlay the audio with video? Are there any recommendations? Ideally I want one of those small microphones where the wire goes under my shirt, and since I am brand new to this, I don't want to spend a whole lot of money, but I'm willing to spend enough money where viewers will hear a clear crisp voice. 

Please feel free to correct any assumptions that may be wrong. I'm also assuming that the Sony a5100 is good enough to get started with a decent picture quality for the purposes of filming me talking in front of a camera in my office. 

Thank you in advance for reading and answering.