Not to be preachy again, but that is the kind of thing engineers do. I'm not entirely sure which 2600 page document you are referring to, but if it is the typical PDF from STM, it has a clickable index. Also Cube comes with digital I/O examples. I had not only pin toggling, but PWM happening in less than a day of playing with that. Also the automatic code generation for peripheral configuration offered by CubeMX is nothing short of brilliant, you can click on a pin, make it an output, and MX will generate the setup code for it. As well as the fancier stuff like clocks and timers. It makes it a breeze compared with coding it manually. Disclaimer - I am not affiliated with STM.