I have a bunch of laptops that I’m in the process of (slowly) updating to the May 1903 update. Microsoft says it’s easy: type “Windows Update” in the Windows search box or:
Go to: Settings > Update & Security > Windows Update and select Check for updates. Once the update appears, you can select Download and install now.
—How to get the Windows 10 May 2019 Update*, Microsoft, May 21, 2019
But there’s a hitch. You may not (probably won’t) see “Download and install now” on your device yet. That’s because Microsoft says, “we are slowly throttling up this availability, while we carefully monitor data and feedback.”