How did you gain the general history you had before? Through years of sitting through courses, years of watching television, years of watching the news or hearing it discussed, there's no Matrix option of just uploading this stuff and large general histories are overall not very helpful and will leave you with more bad understandings than good.

So do you need to sit in a classroom for 10 years again? No. But you do need to start slowly, and build up the knowledge. Pick a topic you are somewhat familiar with as a base point. Read a book about it, figure out which parts of that were interesting to you, read a book about that. Look through the sources that were discussed, look through the historians that were argued against, read their works. Branch out or in depending on how interested or not you are.

Don't hyperfocus either. One common trap is for people to start reading a history book and feeling like they need to look up every single person, every single place, every single event mentioned that they don't automatically know. Instead, just take a note, and come back to it later if you feel like you want to. If you try and master every single page from day one you're going to get overwhelmed and more confused than anything.