Have you tried using the Security menu item provided in the XAMPP Welcome Page left menu frame instead of the command line - much easier?
The instructions are in the readme_en.txt file under the heading:
A matter of security (A MUST READ!)Go to
http://localhost/security in your browser.
Click on the link provided after scrolling down the page perhaps - also there may be a delay while the page fully loads.
BTW you don't edit the mysqladmin file you use a command prompt.
For editing the config.inc.php file or any php, conf or ini file you simply drag it in to an open text editor but if you use the facility I mentioned above you will not need to edit any files - and be careful editing configuration file unless you know what you are doing or you will have unpredictable issues that may be difficult to solve, always make a backup first.