Hello,
Thanks for reaching out! I'm Microsoft user like you.
I can understand you wish to use HDD and SSD same time.
Are you able to see both HDD and SSD in BIOS ?
Also press F12 after during Boot and see if you are able to see both Drives and any option to boot any one of them.
In case of additional questions, reach out back to me, and I will be happy to help and try our best to resolve your issue.
Best Regards,
Prakash