Well, I was 'online' in 1990, but, it sure wasn't 'online' in the same way we know of it now.
My first computer was an IBM PS1 and it was supposed to just be a writing tool. My modem was a slow as heck screeching nuisance, and loading a web page, in the beginning, was measured in minutes, not 1-3 seconds. I spent a lot of time chatting on mIRC programs, mainly ICQ.
95% of my internet experience was primarily between 2000 and 2005. Hard to believe I did so much, on so many forums within 3 years. The forum thing for me died a slow death from 2005 to 2007. It was really never the same after 2007. The last 10 years has been mostly a big hole. The last 4 have been massive doses of major life change.
My board game wargaming never reeeeally made it into this century. My computer based wargaming was primarily from 2000 to 2003.
I'd have never ended up a computer-based wargamer if not for Steel Panthers World at War. Prior to SPWaW, I'd have flat out laughed at the notion you could play a wargame on a computer :)
As such, almost all of my computer wargaming was essentially as a result of my encountering Matrix Games in 2000.
I learned most of what I know about computers thanks to a young lad I met in the 90s that was instrumental in teaching me how to burn copies of SPWaW to cd :)