Please see Windows Subsystem for Linux Installation Guide for Windows 10. If you want to run Linux GUI apps, also see Run Linux GUI apps on the Windows Subsystem for Linux (preview).
Get AOSC OS on WSL
It's the easiest way to get AOSC OS on WSL from Microsoft Store.
If you're running a Windows Server or Long-Term Servicing (LTSC) desktop OS SKU that doesn't support Microsoft Store, or your corporate network policies and/or admins to not permit Microsoft Store usage in your environment, you can get AOSC OS on WSL for your architecture from GitHub Releases. Extract all files from the compressed folder, then run Install.ps1 in it.
Configure AOSC OS
Please see Create a user account and password for your new Linux distribution, AOSC OS also uses apt to manage packages.