I am dealing with creation of symbols in symbol libraries for placing on schematic.
Spice is for simulation. That will need different libraries.
Now you have the folders you mentioned in the opening post, follow the FAQ to create symbol libraries to place in your symbol folder. You will probably eventually need many symbol libraries. eg. transformers, ICs, passives (resistors & capacitors) etc.
Nah I’m not that involved. I’ve only made 2 PCBs this year and probably won’t have the time to make any until towards the end of the year. So be my guest.