php contact form question (noob)

I want to update my contact forms and other forms to have captcha, validation, etc. Does my form containing page have to be a .php (which I have no clue how to edit) or can I still have those things with my form residing on a .html and just have the forms call the .php from a separate file?

Yes, they will need to be PHP because the captcha stuff is a mix of PHP and HTML.
In fact, you may want to utilize AJAX, or JQuery, which is javascripting w/PHP.

If you really want, you can tell your server to process .html filetypes as PHP.
That means .html, .htm, .php all process as PHP. If there is no PHP in them, they
just work like regular .html files.

That is done using .htaccess
You can Google: .htaccess process html as php

thanks