HTML prgramming

It depends what you're aiming to go for. If you're looking more into web development then definitely take a look at HTML and CSS as those are the basics for building a clean website. Afterwards, you can delve into jQuery, Javascript, PHP and MySQL which allows you to perform actions such as user registration systems, live RSS based newsfeeds, dynamic updated content and cool things such as hiding certain areas of your website. Be noted though that CSS is good enough when it comes to changing certain things like creating irregular shapes, gradients and transitions (scrolling slower for instance).

As for "programs", take a look at Notepad++, Brackets.io, VSCode or Sublime Text. They're all great code editors with good syntax highlighting and Sublime/VSCode have a built-in plugin feature. Brackets by default has live preview but you can get that on VSCode and Sublime aswell, so you can see what you're creating as soon as you make changes.