how to know who visited my website
By locating IP address.
Hi @PatrickThuku welcome to the community and thanks for your question.
You could embed some code in your website which, as @SimonaSalnaja mentioned, captures their IP address to find out their location. Try sites like https://www.freecounterstat.com/ to investigate if this is the kind of thing you need before looking at Google Analytics etc. I’m sure others in the community have their favourites too!
Like the actual person’s name? I can think of one solution: use authentication to make people be recognizable, and then put the username (and quite possibly the date they joined the website) in a text file to know who visited your website. That is the way to know who specifically joined.
To get more general details, I would have told you to analytics but I can’t find it for some reason.