I could explain it in detail, but that very often becomes a protracted and tedious process in a forum setting such as this. It actually encompasses instructions on how to set up and administer your home WordPress development environment and private network settings. Both are beyond the scope of what the forum is actually for.
My best recommendation is to start by consulting Google for popular tutorials and documentation on installing and configuring XAMPP for development use with WordPress, on whatever OS you have it installed on. Be specific in your keyword searches and you should be able to find tons of good how-to’s and documentation. It might take some time, but it makes more sense as you start to learn and progress.