I need some step by step instruction please

I plan to put a 1tb m.2 drive and a 2tb hhd in my new build computer. I am not familiar at all on how to partition the m.2 drive into drive C and D. C having 1/3 of the capacity for OS and programs, and D for data. I understand I put the M.2 alone in the system and worry about the HDD later.

Now I have the 1tb M.2 install and I have the OS in the installation media (USB). Can someone give me a step by step instruction to install Windows 10 into the Drive C and allocate 350gb for it, and...

I need some step by step instruction please