Once you've checked your target system meets the necessary requirements, then you will need to select which edition you want to download. There are a few different Windows 11 editions to choose from, but we'd suggest, unless you're specifically after the China edition, that you go for either of the top two options.
There's a Dev channel and a Beta channel edition for the Windows 11 Insider Preview and the difference is purely based on the cadence of future releases. The Dev channel of the Insider Program will get the latest updates, but that also means they risk being the least stable of builds. The Beta channel, therefore, is likely to be a more solid release.
So, it depends if you're willing to experience the odd bug to experiment with the latest Windows 11 toys.
Then select your preferred language set and download the ISO file.