How to display your code to the ussry

Question

I'm still kinda new to php, but I've been wondering if perhaps there is a way to display your code as a kind of graphical interface or something.
For instance :
A code that checks if a year is a leap year. How can I create a web page where a user can input a year and may be click a button instead of having to input the year manually from the code?

Answer 1

... and JavaScript ^^

Answer 2

You should learn HTML and CSS.

Answer 3

Yeah. I know html and css