Spring usage within this application

EDIT: I think this should be moved to the beginner section or another part of the Forum

I know I may get slated with this question. I apologise in advance but if you knew what was at stake with knowing this you may understand.

About 6 years ago I started Java development, then about 3 years ago I was hired as a web developer to develop an application. Unfortunately my skill set lies in ASP.NET so it was a learning curve. I came across this tutorial;

http://www.roseindia.net/struts/hibernate-spring/index.shtml

It was a GREAT starting point, and for the next 6 months I used this as a starting point to develop a massive application ontop. More and more components were added but I used the underlying Hibernate, Spring, Struts concept.

However, now I am going for my DREAM job, and need to present this application. The commercial, planning, and extra stuff that I added, I could talk about until the cows come home, however, I know my knowledge of what goes on underneath is lacking. Plus, because its my first real Web application and I used all these technologies, I cant really say WHY I used them... I used them because they were in that tutorial!!

If someone could have a look at the source code to that project, and see how its put together and help me, you would literally save my life!

I understand each part individually (Except the Spring element). Hibernate is used for ORM, and Struts was used instead of JSP/Servlet so the mapping could be taken to a config file. Thats all fine. Hell, I even know how it all works (or I wouldnt have been able to expand on it) however, I need to know MORE. And in more and more detail.

Why has he used Spring. what is it doing that I couldn't do WITHOUT spring. What is it doing to interact with Hibernate, and Struts? What are the alternatives, and what are the benefits. What are the constraints? Etc etc

I apologise again for this question. I know i need to go back to the learning drawing board and have a more structured approach to knowing about these technologies. However that wont get me through Next weeks interview. I have no-one to ask so any help would be amazing

I moved this to jobs discussion.

It's ok to say that you used those technologies because you heard they were popular. Any good interview is going to notice you don't have a lot of experience in this space. And that's ok if you admit that.

Thanks for your reply (and moving the topic).

Could you give me a hand in talking high level about the project. I know if I sat down and CODED the project, I would be fine. Categorising what I am doing however, is not my strong point. For example, saying it takes a MVC approach, as apose to just going on about how I can split up what you see on the page and the code that runs underneath it... terrible example I know. But a paragraph summarising the project I am on about would be great.