tl;dr, you write compressed notes, or cornell notes style, which is all the concepts presented to you in a semester. You then attempt to teach these concepts to an invisible class: "If you can’t, out loud or on paper, explain the idea without confusion or contradiction, stop and figure it out right there."
If you've been an end-user for most of your life, you are probably good at user interface design having used an endless sequence of shitty UI. This course has almost everything open like recorded lectures http://www.cs.cmu.edu/~bam/uicourse/05863fall17/schedule.htm... then go about practicing by redesigning free templates for Shopify/Wordpress or create your own.
CS curriculum for me consisted entirely of terribly boring Java courses to the point I considered dropping out, as I was just doing the bare minimum of work to stay afloat, until I abandoned the recommended curriculum and started taking complexity theory classes. Theoretical CS for me at least was motivating and interesting, maybe it will be for you, go through some of this playlist, see if you're interested. If you are then if it's possible try to re-enroll in university, and use expii.com to practice basic math https://www.youtube.com/channel/UCWnu2XymDtORV--qG2uG5eQ/pla...