First of all, let me say I'm using LyX, though I have no problem using ERT.
Secondly, what is the most simplest way to draw a simple graph like this in Latex?
I've seen some documents with graphs and I've seen some examples, but I couldn't figure out how to just draw a simple graph – what packages do I need, etc?
Best Answer
TikZ can do this.
A quick demo:
produces:
More examples @ http://www.texample.net/tikz/examples/tag/graphs/
More information about TikZ: http://sourceforge.net/projects/pgf/ where I guess an installation guide will also be present.