To be able to judge about the quality of your own pictures your monitor should be of good quality and calibrated. This means, that brightness, contrast, gamma values and colors match reality. This is much more important, when you want to work on pictures. Otherwise, if the monitor calibration is wrong or not done at all, it can easily happen that you make the pictures worse as you cannot properly assess your corrections.
When you use Windows 7 or 10 there is the very little know program dccw.exe (the letters stand for Display Color Calibration Tool for Windows) for calibrating your monitor.
For starting it press your windows key once and type dccw.exe (in the search field) and press enter.
Starting the program dccw.exe over the search field in Windows 7
... or press the key combination windows + R to open up the execute window and type dccw.exe there to start the software for monitor calibration.
Starting the program dccw.exe with Windows + R
Now read the instructions and follow them.
Display Color Calibration Tool for Windows in use
Author: Axel Pratzner
Translator: Felix Pratzner