If you are looking to understand how to build support for a keyboard head to the Porting a keyboard to VIA section of the docs.
Hop over to the download page to make sure you have the latest build.
Unpackage the download and launch the
If you discover any bugs please raise an issue.
Using Vial is extremely simple, just click on a key you would like to change the value of in the top palette then select your replacement key or macro in the bottom palette.
Your new key will be automatically saved onto the keyboard and immediately ready for use.