If you are completely new to sound synthesis, I would recommend starting with a used/low-cost synth or groovebox or even some basic synth software prior to jumping into modular. It's an expensive and complex place to start learning the basics. You won't have everything you need to make entire sounds (aka full "voices") unless you get a ready-made system. As a true beginner you'll get much more out of an all-in-one machine. A crawl->walk->run sort of thing.
If you are deadset on starting directly with modular, a Moog Mother-32 (or another semi-modular) may be something to look at. You'll outgrow it as a stand alone but you can use it to start to build your modular system.
Also, the manuals for most stand-alone synths assume the user has no prior knowledge. Most of the time they will have an introduction to sound synthesis. Even downloading a manual for a "virtual analogue" synth and reading the introduction will help. Most module manuals (IF they even have one) assume you know the basics already.