Somewhere on your disk, you create a new text file, for example
begin.txt, and put this in it:
This is how I've begun with Latex.
Now you rename that file to
Open it. With my last proTeXt installation that fired up TeXStudio on that document, I needed only press
F1, and a pdf was created.
Next you decide what you want to achieve with LaTeX, and look for likely examples online, and in books, and you figure out the LaTeX commands as you go along. It takes some dedication, but soon you realise how amenable LaTeX is.
I find a lot of the power and freedom of creating documents in LaTeX comes from using my preferred text editor, gVim in my case. Also, as I'm working on an old netbook, I'm avoiding opening a resource heavy WYSIWYG word-processor program.