Couldn’t install windows 10 using boot camp assistant

[taydui]

I have a MacBook Air mid 2013 running high Sierra with 256gb SSD. Trying to install windows 10 pro (iso) using bootcamp assistant. Made it to where you select the drive (labeled bootcamp) to install windows but the “next “ is greyed out that’s where everything stops. What do I have to do to get windows installed please ? Any advice is greatly appreciated