Violma and I know the basic coding languages (HTML, CSS, Java, jQuery)
In any case, you need a sever-side language, as well as a database and some knowledge on how to interact with the database in your chosen server-side language (and maybe a web framework in that language as your, well, framework to build upon). There are quite a few to choose from, and if you ask a dozen random web developers from around the world in different sectors of the business, you'll probably get at least 8 or 9 different recommendations as to which is "best".
And as I mentioned above, you'll want to learn at least the basics of databases (probably at least starting out with relational databases -- RDBMS -- such as MySQL or PostgreSQL. Ultimately all your dynamic data (users, posts, comments, etc.) will need to be stored in some sort of database.