New to HTML and CSS

I've been actively learning how to use HTML & CSS the past three days, so if this sounds like a dumb question, it definitely is.

I was wondering how one would code a textbar that you have to input a exact set of characters to pass onto another page. Not an email or a name input but if I could make a specific word/combination that they have to input to then be passed to the next desired place I chose.

I've tried googling this for awhile but haven't been able to find anything :/ thank you in advance!