Please dumb this down for me (Aikido leg lock)?

Liondancer is right, you need someone to demonstrate this technique for you or you will lose the nuances in the technique that makes it work. But to answer your question, You are correct about the Nage and Uke part. Ryu kata dori is a designated attack given to an Uke, in this case it means he must attack Nage with a two handed lapel or shoulder grab. Atemi is any distraction whether in the form of a strike or feint that makes the Uke flinch and lose his focus and unbalance him, thereby giving Nage the opportunity to apply a throw or lock/pin. As for the leg lock, it's not exclusively found in Aikido only, it's a technique common to most other arts from Jujutsu to Karate even Kung Fu, so you can't really attribute it as unique to Aikido only. You'd be better off using the technique called Irimi Nage as an example as this is not as common in other arts, but as stated you need a qualified instructor to show you how it's done properly and explain it's principles to you. It's not something you can explain over the internet. Much as I can appreciate your desire and intent to promote the principles of Aikido and it's techniques by writing a report about it, I think that task is best left to experienced practitioners of the art who more qualified to explain it better to lay persons. At most, you might mistakenly create a misconception about the art, since as you have admitted, you know next to nothing about it and may only end up creating more confusion about an already misunderstood art. But if you really are interested to write a report about Aikido, my suggestion is to read up about the life of it's founder Morehei Ueshiba O' Sensei and how he came to develop his art. I think that would make a much more interesting report instead of a written technical breakdown of individual Aikido techniques.