[sdiy] simple analog sinth

[luca rossini]

good morning,
i'm a new-entered physics italian student who would like to build a SIMPLE 
(almost primordial, just to start and understand) analog synthesizer.
i'd like to ask anyone who has time to answer how should i build the 
fundamentals:
where do i get frequencies? how to modulate them? umtil now i can only find on 
the web some technical informatioins, but never a starting scheme.
how to build an oscillator? i need help!

thanking you in advance, i send my best regards
luca rossini