1. Take the file 'FreeCAD-filename-SHA256.txt'
2. Save it to the location of the file you want to checksum
3. Rename it so that you replace 'filename' with the name of your file you want to checksum.
   Thereby don't forget that the file ending has to be part of the name.
4. Open the file in a text editor

5.
* Either (if you have 7-Zip installed):
  1. right-click on the file you want to checksum
  2. select in the context menu "7-Zip -> CRC SHA -> SHA-256"
  3. copy the content of the appearing dialog to the text file
  
* Or
  1. run Windows' 'certutil' utility in the command line, e.g.:
     certutil -hashfile FreeCAD-0.20.0-WIN-x64-installer-1.exe SHA256
  2. Copy the resulting hash from the command line to the file
  3. Update file size and filename in the file 