Problems with Fusion Drive config

Hi, eveannwallis, i had the imac 21.5" with a core i5 and a fusion drive with 8 of ram, i replace with a core i7 7700, 32gb of ram, the proprietary NVMe of 32gb i replaced it with a 256gb and the mechanical drive replaced with a 500 gb ssd 2.5, now the problems is that a can not (or a don't know) fusion back the two drives, also when try to install windows through the bootcamp does not let me do it :( ..... i sow a tutorial

https://www.youtube.com/watch?v=2F2RkwOV...

i have to try that to see if it works....