What do I do now and how do I do it? (BootCamp & Engineering student probs)

I'm an engineering student and I really need to get my computer to run software that my classes require, so I decided to install BootCamp. It was a very difficult process, and after much time and patience, I got passed the partitions-step and restarted my computer. When I did that, I was taken to a black screen that mentioned something about a "bootable disk." I called Apple and they said I need to install Windows, but I couldn't do that on the spot so the guy just helped me get my computer to run normally. My question is, how do I move on from here? How do I install Windows on my computer and which one should I use? Also, what kind of disk do I use? I'm not as technology savvy as I should be so please bear with me. FYI, the software I currently use is MathCad Prime and I will be using AutoCAD this quarter. I also have access to free Windows because of the fact that I'm a college student.

ANY HELP IS IMMENSELY APPRECIATED!

Thank you.