Programming for beginners: If want to do back-end web development what are the programming languages and forms I should be learning?

you can begin by HTML, PHP and SQL.

you can learn basic (HTML, CSS, JavaScript) then learn (PHP or Asp.net or node.js) for back-end programming and (SQL, MySQL) for the database

you can begin C, C++, HTML , CSS  

Python, PHP, Node.js, and ASP.NET

For back-end programming, you'll first need a basic understanding of how websites work, how data is transferred over the internet, then you can start learning how computers works (nothing complicated just the basics), after that, HTML/CSS to understand how web pages are built.

Then you can jump to a server-side language, PHP is easy (Python is good too), but if you feel comfortable you can go with ASP.net or JAVA.

you can begin with HTML, Css, PHP, MySQL

HTMl , JavaScript , CSS , PHP

The highly recommended programming language for back-end web development is PHP . It's an open source programming language that we can rely on when developing a back-end website, for example, Facebook is based on PHP from A to Z.

Another trend today is using Python when developing back-end websites.

HTML, CSS, Javascript, PHP and Mysql

you can begin with  HTML, PHP and mySQL(database). 

You will need a basic understanding of C language which is the base of programming and would highly recommend C++ for OOP(Object Oriented Programming).