Hello,
The project you have proposed seems to be a rather simple modal, which I have plenty of experience with.
I would probably start by leveraging the jQuery plugin written, by Jack Moore. It is lightweight (9kb) and I have used it on 3 different projects now.
This sounds like it would only take me a couple of hours and I could write up some notes for you on how to implement it in other parts of the website.
Let me know if you have any questions,
Jack