Combining the answers from Axel Kemper and adding some extra's, here is what I did to make a permanent command that you can give any name you want.
First of all I created an extra folder. In my case: "C:\Users\Hansel\CmdFiles". In this folder I created a new text file throught the right click menu -> new -> text document. Edit the text document using notepad or notepad++ and type the following code in the .txt file:
Then you have to rename the file to your personal command, for example "npp.cmd".
On a side note: the @echo off prevents the command from printing to
the command prompt;
the link between the quotation marks can refer to any executable;
%* will make sure that anything you type after the
npp command (for example "npp nonsense.txt") will be put after the original command in the quotation marks.
Then you need to edit an "environment variable", in this case the so called PATH (this variable contains the folders where Windows looks for commands and executables). To add the folder to your PATH, push the windows button to enter the start menu and type "edit environment variables for your account". Under "User variables for Hansel", create a new "Path" variable if it does not exist or edit the old "Path" variable if there is one.
If you make a new PATH variable, the variable value should just read: C:\Users\Hans\CmdFiles
If you edit an old PATH variable, the variable value should read: oldstuff;C:\Users\Hans\CmdFiles (mind the semi colon).
Windows now looks for commands in the folder "C:\Users\Hansel\CmdFiles" and you can easily add new commands to this folder!