For the sake of this series, we're going to be developing using the .Net Framework, I will discuss this further into the series (for now it's not essential to know just what it is).
If you're completely new to coding, I suggest downloading the Visual Studio IDE (Integrated Development Environment) from MS VS download page
You could also use VS Code Editor, but it's suited for more experienced developers, allowing you to code in multiple languages. In terms of C# VS Code is more utilised for .Net Core development (again more on this further on in the series).
An IDE is an Integrated Development Environment, in essence, it's a code editor with many extra features (code editor, compiling, debugger). Think of an IDE as an all singing all dancing editor.
A text editor is just that, it's a text editing application. However, nowadays they're beginning to branch out with the ability to install extensions, and support languages other than programming languages , such as Markdown and SQL.