You can create and build your online website directly, it's totally not recommended.
It is best to create locally, mainly if you are starting.

WEB SERVER

The first software to install is a local web server.
There are various more or less complete. The main Windows are EasyPhp and Wampserver. MacOS that will MAMP and Linux LAMP or XAMP.

When you ask your browser (such as Firefox, Edge, Chrome or Opera for example) to display a web page, it sends a request to the server with this page which sends.
EasyPhp and Wampserver behave exactly the same way except that they are directly on your machine. There's no information provided on the outside so you can test your site without even having a hosting or even internet access!
It is as if they were posted on the web!

It includes the following Apache, MySQL and PHP. This is what Wikipedia says about their operation:

The roles of these three components are:

• Apache web server is the "frontal": it is "before" all the others and responds directly to the web client applications (browser) 
• The PHP scripting language used logic and allows processing (calculations, verification, test, etc.)
• MySQL to store all application data (database)

(Source : Wikipedia)

EasyPhp

Wampserver

The Guppy CMS

The cms Guppy has the distinction of not possessing like MySQL relational database.

Since version 5.01.00 it is "responsive design" and "mobile friendly", ie it works on all devices, PCs, tablets and smartphones.

It includes an administration interface from which you can activate sercices like blog, news, FAQ, guestbook, links, forum, calendar, information letter and other things you'll find. Online help is in place, with the ability to integrate with your site.

GuppY

 BROWSER

Firefox is clearly the best browser for the development and navigation. Very secure, it offers the ability to add extensions, here are 3 essential.

Firebug an essential extension to scan all the code and identify potential problems

ColorZilla an extension with advanced color pipette, a generator of colors and other features

Web Developer an extension that integrates a set of code control tools

Mozilla Firefox

TEXT EDITOR

Under Windows, the notebook is not made for development. Install Notepad ++, this is the most comprehensive.

Notepad++

FTP SOFTWARE

To transfer your files you will need an FTP client (File Transfer Protocol) to exchange files between your local PC and the remote server.

On Windows, there either no hesitation, FileZilla is the tool you need.

Filezilla

GRAPHICS

A website is nothing without some graphics. Without necessarily being a pro of the composition, you will probably need to do the editing, either on the overall design of the site or the photos you'll probably have to upload.

There are many software, more or less complete, more or less complex.

To stay in the field of free and/or open source software, our choice will be limited to these two titles:

Paint.NET

Gimp