The most popular "how to synthesize" article series is Synth Secrets which ran in Sound on Sound Magazine over a period of years. You can find those online.
Regarding what tool to use, a modular like this(albeit in physical, analog form) is the "original" way to do it. Modular sound can do just about anything provided you have the modules and will to program it. Later on in the commercialization of synthesis manufacturers built smaller semi-modular or fixed-path synthesizers which don't let you patch anything anywhere but are considerably simpler to achieve a result with since their basic architectures expose all the essentials of sound character without being so much of a programming exercise: the Minimoog and Oberheim SEM, to name two, just sound good out of the box and generally sound good no matter how you turn the knobs, and their designs are widely cloned even today.
This era lasted roughly from the early 70s through the early 80s after which synth programming soon became complicated again, this time by digital technology allowing everything to be tweaked and patched and perfectly recalled from memory, provided you were willing to dive through menus. Synth programming turned into a speciality in this era; everyone who just wanted a sound used the built-in presets.
Regarding what tool to use, a modular like this(albeit in physical, analog form) is the "original" way to do it. Modular sound can do just about anything provided you have the modules and will to program it. Later on in the commercialization of synthesis manufacturers built smaller semi-modular or fixed-path synthesizers which don't let you patch anything anywhere but are considerably simpler to achieve a result with since their basic architectures expose all the essentials of sound character without being so much of a programming exercise: the Minimoog and Oberheim SEM, to name two, just sound good out of the box and generally sound good no matter how you turn the knobs, and their designs are widely cloned even today.
This era lasted roughly from the early 70s through the early 80s after which synth programming soon became complicated again, this time by digital technology allowing everything to be tweaked and patched and perfectly recalled from memory, provided you were willing to dive through menus. Synth programming turned into a speciality in this era; everyone who just wanted a sound used the built-in presets.