When I was 10, my sister was learning QBASIC at high school. As most younger siblings do, I harassed my sister to entertain me almost constantly. Eventually, my sister got annoyed with me and handed me some floppy disks with games on them so I would leave her alone. These games were written in QBASIC and the files were not compiled, so I had to open the IDE (or the equivalent of) to play them. After I quickly got bored with the rather simple games, I started to mess around with the QBASIC code to see what would happen if I changed things around.
From this, I taught myself how to make my own programs; these were usually quizzes that I asked everyone in my family to complete and usually were some form of Harry Potter trivia (I was seriously obsessed). My sister was also learning HTML at school and those floppy disks contained some of the websites she'd built. They were your typical 90s web design fare with animated GIFs, marquee and blink tags, and clashing colour schemes. As with the QBASIC programs, I opened these webpages up (with some guidance from my sister) in Notepad and started moving things about to figure out what was going on. This was late 1990s, early 2000s and we had the internet but my mum ran a business so I was only allowed two hours a week on the internet in one hour blocks so I didn't tie up the phone line for too long.