There are many skills, technologies and languages that can be utilised to develop and maintain web sites. A good starting point is the Hypertext markup Language (HTML) and Cascading Style Sheet (CSS) followed by JavaScript tutorials. This will enable you to develop static web sites.
For a static site all you need is an editor and a browser, and a web server to test the site before hosting on the web. IDEs are developer's friend and frameworks are indispensible for larger projects. For a dynamic site, you need to decide which language and install the appropriate servers.
Here are several free open source programs that should meet all your needs.