So i am going to build a Computer soon and will be getting a SSD and a regular 1TB HDD, can i install windows on both of them or combine them somehow and use the SSD as a start up for the OS and stuff while the HDD is just for storage, if i use the HDD for storage, do i need an OS on it?
No, one OS one install. An SSD is wasted if used as a cache for Intel RST. Install the OS on the SSD BEFORE you attach the HDD to insure that the SRP (system reserved partition) ends up on the SSD. Then attach the HDD and configure it in disk management.
Use the SSD for you OS and most commonly used programs/games, other programs/games on the HDD along with data.