Determining the Order Files Are Run in a Website Built By Someone Else
Try opening in the page in Chrome and hitting F12 - there's a tonne of developer tools and web page debuggers in there.
For your particular question about loading order, check the Network tab, then hit refresh on your page - it'll show you every file that the browser loads, starting with the HTML in your browsers address bar. 
If you're trying to figure out javascript, check out the Sources tab. It even allows you to create break points -very handy for following along with a page is doing.
Ok, this question is going to sound pretty dumb, but I'm an absolute novice when it comes to web development and have been tasked with fixing a website for my job (that has absolutely nothing in the way of documentation).
Basically, I'm wondering if there is any tool or method for tracking the order a website loads files when it is used. I just want to know a very high-level order of the pipeline. The app I've been tasked with maintaining is written in a mix of django, javascript, and HTML (none of which I really know, besides some basic django). I can understand how django works, and I kind of understand what's going on with HTML, but (for instance) I'm at a complete loss as to how the HTML code is calling javascript, and how that information is transfered back to HTML. I wish I could show the code I'm using, but it can't be released publicly. 
I'm looking for what amounts to a debugger that will let me step through each file of code, but I don't think it works like that for web development.
Thank you