i am going to start a solo league and i need some info
 

i am going to start at the earliest date which think is 1879 but i was looking at the mod section and there are some of the mods i'd love to use but have no idea where to put them in my league when i start it, i am new to this, the big things in the mod section i would like to add is the real team logos, real faces, real stadiums, but as i said i have no idea where to start

You can start a historical league in 1871, you can start a fictional league with any year to my knowledge.
If you can add many of them through add ons central, some thing only work with anew game not an existing one. everything else you can pretty much put into the ootp folders or load them manually through various screens. FG's or photos go into the ootp folders for them.