Okay so I appreciate everyone's advice since it's helped me get a better understanding of what I need and have to do.
That said, I ran into a snag at Office Depot. On my first attempt, as I said earlier, we used matte legal paper and the image turned out to be too big. After cutting it out, it was far too large to fit in my UGC. I assume this happened because it was printed with fit to paper on (scale to media?).
When I went back tonight, I mentioned this to the guy and he made some changes. We made sure the orientation is landscape. I checked to make sure the horizontal/vertical resolution of the image is 300dpi. I believe it was centered both horizontally and vertically. I wasn't sure about how to have borders being set to minimum though.
What happened was this (see below).

This is what the print-out looked like after the white around it was trimmed out (It was
not trimmed too much, that is what it was printed out like). As you can see, it looks like the image is cropped too much, especially at the top and bottom. I don't know what the specific problem is and maybe someone can help me figure that out? What were we doing wrong tonight?