Javascript : find first unchecked box and retrieve information from row

So I am trying to find a way to extract data from the first row where the checkbox from the first column is unchecked. I know this may sound like a true beginner question but I couldn't manage to find how to do it despite searching for quite a few hours.

Here a step-by-step of my goal to clarify :

1. Find the first checkbox which is unchecked;
2. Retrieve information from another column (inner html) but from the corresponding row and an attribute ("name") of the checkbox;
3. Without opening it on-screen, use the attribute of the checkbox (partial URL) to open completed URL and retrieve more information into MySQL;
4. Check the checkbox;
5. Rince and repeat

I am only looking for info concerning step one and two, the rest is there for clarification. I do not have prior experience in Javascript writing prior my last few days of Internet browsing, the only coding I've done were statistical analysis in R.

Any help would be highly appreciated.

Thank you very much!

Nikola