Form method get and post, haha -
This was back in the mid 90s / mid teens - documentation was garbage obviously - I knew how to create a form and input fields but it took forever to realize that data had to post to some sort of language NOT html in order to do anything with it.
Which is why I probably fell in love with PHP. Compared to the only real alternative - CGI-Bin - PHP made it really easy to process that form request.