I have been in the field for so long that I have quite forgotten what it was like to be a beginner. We were pretty much all beginners back then, so there weren't many sources of info beyond on-the-job training and trial-and-error. Several decades ago I did take several courses in specific things that were new and that I needed to know.
I originally got into it via data entry on devices so cumbersome to use that most "kids these days" would not believe how we had to do things on computers (think "Position eight switches, up for 1 and down for 0, and then hitting a button marked "Commit" for each individual byte), but I was always interested in the field anyhow.
I would suggest starting with a simplified book like "Windows 8.1 for Dummies" ($13.17 on Amazon) and also looking at some other sources about hardware, peripherals, and applications like your web browser, email client, graphics apps, and an office suite like MS Office. YouTube has videos on the subject by the thousand.
You can of course take courses on nearly everything involving information technology, but I would suggest starting from the most general and then working toward the most specific. Some of these are offered for free in local government-operated community centers.
I would also suggest looking at some of the YouTube videos about how to build your own desktop computer. While actually building one might be an ambitious goal (although it's easier than you probably think), it might also provide a cursory understanding about what's in a computer and what the various components like the motherboard, the main processor, the power supply, the RAM, the external ports, and the storage devices are and how they interconnect.
You might also want to learn a little bit about networking, because this is where you will find the most frequently encountered problems on any given day. The main thing you need to know here, though, is the phone number of your cable company's technical support, but it doesn't hurt to have enough knowledge to be able to accurately describe the problem to them.
This is a huge field and you will NEVER stop learning -- I certainly haven't. One of the chief aspects to it is that the best way to learn is by doing, keeping in mind two essential rules: In email, NEVER open an attachment, and NEVER click on a link you can't identify, unless you ALREADY KNOW what it is. Violating these rules gets more people in trouble than anything else in the whole IT world.