Hello
Welcome to Shapeways. I started off in a similar position last autumn.
Following recommendations here, I picked up Blender (www.blender.org), a freeware program, and am quite happy with it. They also have good manuals and tutorials on their site. That said, it still took me several weeks of dabbling to get to my
first model. With experience, you get much quicker than that,
AFAIK, there is no Software that allows you to enter a 3-view drawing and get out a 3d-Model. It is possible to use a set of pictures to make a 3d-Item, but you need something like 50 pictures from a lot of angles.
But Blender allows you to put an image as background to the screen, so you can model off that.
Greetings
Karl Heinz