This question already has an answer here:
I just built a new PC, and I'm looking to dual boot Windows and Ubuntu. I have a 256gb SSD, which I would rather be dedicated to Windows. I also have a 2tb hard drive, which is where I'd like to put Ubuntu. I'd like Ubuntu to take about 256gb on the HDD, with about 1.75tb of shared storage for both Ubuntu and Windows. How would I go about doing this?