@aanee What I'd recommend is to get an already working device and to find a component with available datasheet and missing functionality in its kernel driver. There should be plenty of such bite-sized low hanging fruits out there, which will let you gain enough experience to work on and debug more complex stuff with devices that aren't ported yet.
I don't know how a "porting for dummies" guide could even look like, this kind of stuff tends to be highly device-specific.