Do I need to install MiKTEX on my system before installing Texmaker or Texmaker will work even without installing MiKTEX?
If you want to run LaTeX on Windows you need to install a TeX distribution for Windows, MiKTeX or TeX Live.
pdflatex mwe.tex you can then compile the TeX code in file
mwe.tex from terminal/console.
So we need a programm, an editor, to create such a file
For example TeXmaker, TeXworks, TeXstudio, TeXnicCenter, WinEdt, Notepad++, etc.
A "good TeX editor" knows about the two distributions so it makes life easier, if you install the editor after the tex distribution, because the editor can recognize which distribution is installed and can do an automatic configuration.
Do you install the editor first you have to do the complete configuration by your own.
That's the reason you should first install the tex distribution and then the editor.
The editor is only to create a file containing the TeX code to be compiled with the TeX distribution. Without TeX distribution you get no pdf file!