How do i connect capture to ndi prieview in vista

hello, i’ve recently learned roughly about ndi preview and it’s capabilities. the issue is i can’t figure out how to connect capture to ndi preview. ive tried looking at user manuals, youtube, and the vista fourms but i can’t find anything. if somone could provide a youtube video or step by step instructions on how to connect it. that would be appriciated. thank you!