I believe others already mentioned some books, and sites for learning.
I'll just say to start by moving knobs around, and try out different filters or waves. Just play around with the synth for a while each day.
I never studied any "how to" synth books, except for some manual pages.
I just learned by doing, and also observing the sounds of others, to see what was done.
So I'd suggest, just study synths with your ears, and mouse turning knobs, and clicking buttons.
Of course the reading helps too...to an extent.

I'd suggest learning on U-he Zebra.
It's got a great demo, as no noise, an can load, and save presets.
It needs to be reloaded in your DAW about every 10 minutes.
You can download that here.
http://www.u-he.com/cms/zebra
You can also load some free presets with it here.
http://www.u-he.com/PatchLib/zebra.html

To learn with Zebra, you can just move 1 oscillator and 1 filter to the mod grid, and just work with those to start...adding modulations, and other modules as you get more familiar with it.

Good luck.

We have lots of video tutorials that will help you get started on synth basics

http://www.youtube.com/playlist?list=PL366C9BA223C09B48&feat ure=plcp

http://www.youtube.com/playlist?list=PL4A15553A4CF6E4EB&feat ure=plcp

http://www.youtube.com/user/discodspcom?feature=mhee

A little example

http://www.youtube.com/watch?v=Nk74l6gMQ1U&feature=youtu.be