You will most likely try a few different cad programs to find the one you like. Play with a few and see what you think. One that I use is Qcad. I have tried quit a few others but I always come back to it. It's a fairly easy to use 2D program that has online manuals. I use it everyday to design and prepare my files for the laser cutter. Here is a photo of the Flyline Great Lakes I have put into Qcad.
Qcad information can be found here. http://www.qcad.org/en/qcad