Early 1990s, writing HTML tutorials on a site I called "Website Goodies". I learned HTML myself from a GeoCities site. I had ads on there from the start, from TeknoSurf AdWave (now Advertising.com), ValueClick (now Conversant), and IIRC briefly some kind of ads from Microsoft bCentral (defunct). Enough to pay for the domain and web hosting, and eventually enough to buy a computer of my own and cable internet from @HOME under a parent's name.
WSG started with articles (outdated and long gone now), then I started adding "tools" as I learned to program. Originally they were all CGI scripts written in Perl with text files for storage. Later PHP and MySQL after reading Kevin Yank's tutorial, which was later picked up by SitePoint as a book, now on its 4th edition. I made hosted guestbooks, a banner rotator, a hosted hit counter, things like that. At some point I came to know of hosted web analytics tools. This was long before Google Analytics, and the cool looking ones were B2B products that cost way more than I could afford.
I made my own web stats program. Each website got a separate log table with a couple hundred rows before I purged old entries. Real-time reports based on querying that log for the top pages, top referrers, etc. I learned to use PHP and GD to draw numbers on images, made a bunch of counter backgrounds in Paint Shop Pro, and offered customizable counters that doubled as the tags for logging to the database for the reports. At some point I decided to move it to its own domain, and chose W3Counter for world wide web counter.
By that point I had just graduated high school. Got serious about earning enough to pay bills, started a bunch of e-commerce sites. That's when I found a need for e-commerce conversion tracking, and being too cheap to pay for it, made another analytics tool for that. Eventually rewrote it and tried to sell it SaaS as the poorly named "W3ROI". Learned from the couple dozen people I got to try it, started over from scratch in 2012 and Improvely was the result.