In the first place is code editor of course! Without it, you will not move. For CSS file you need to use only gedit. It is typical userfriendly graphical Linux text editor. However, if you use a programming language, you will need something better. You can download Geany. It has syntax coloring, file functions, objects and classes manager. If you would like something more you then should install NeatBeans. However, for people who like terminal the best choose will be vi or emacs. They are the most popular Linux text editors. The second step is installation of WWW server with PHP, and some database. On Linux you have got a lot of possibilities. The most popular WWW servers are Apache2, Nginx and LightHTTPd. Apache is the most widely used HTTP server on the Internet. It supports: CGI, proxy, FTP, mod_proxy, SSI, SSL, mod_perl, pod_php, etc. The latest version of Apache has also a graphical user interface. Repository of Linux System is rich in database packages. Users can install PostgreSQL, MySQL, SQLite, Redis, MongoDB and more others. However, an ownership of own server has got few defects. At first and the most important is an independent configuration of system. It has to be safety, primary! Users, who are not familiar with the topic will have got a huge problem of it. Then, user can put a local server (via 127.0.0.1), without an output traffic. But, there is a big advantage of having your own server - user can modify of server settings arbitrarily, as he/she would like. Of course, if we need output traffic, we can put own server. Nowadays, a lot of companies service a hosting, so every user/developer/admin can buy some virtual host or a real server. The most popular hosting companies which have Linux machines are Microsoft Azure, OVH, SoYouStart, Hetzner, etc.
The next step of installation system for WWW is a FTP client. Good client can while life away. Of course, we can use some browser widget, but it is not very comfortable. Personally, I like FileZilla (it is available in repositories). It supports a FTP and SFTP connection. The most users use gFTP too, but it does not have a possibilities of maintenance more than one connection. If we have an own host outside the local network we must put FTP server too. I prefer protFTP, because it is not difficult and intuitive program.